![Toronto by Sentinel-2](https://upload.wikimedia.org/wikipedia/commons/9/96/Toronto_by_Sentinel-2.jpg)
The geography of
Toronto
Toronto ( ; or ) is the capital city of the Canadian province of Ontario. With a recorded population of 2,794,356 in 2021, it is the most populous city in Canada and the fourth most populous city in North America. The city is the ancho ...
,
Ontario
Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
, covers an area of and is bounded by
Lake Ontario
Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north, west, and southwest by the Canadian province of Ontario, and on the south and east by the U.S. state of New York. The Canada–United States border sp ...
to the south;
Etobicoke Creek
Etobicoke Creek is a river in the Greater Toronto Area of Ontario, Canada. It is a tributary of Lake Ontario and runs from Caledon, Ontario, Caledon to southern Etobicoke, part of the City of Toronto. The creek is within the jurisdiction of the ...
,
Eglinton Avenue
Eglinton Avenue is a major east–west arterial thoroughfare in Toronto and Mississauga in the Canadian province of Ontario. The street begins at Highway 407 (but does not interchange with the tollway) at the western limits of Mississauga, as a ...
, and
Highway 427
The following highways are numbered 427:
Canada
*Manitoba Provincial Road 427
* Ontario Highway 427
India
*National Highway 427 (India)
Japan
* Japan National Route 427
United States
* County Road 427 (Seminole County, Florida)
* Indi ...
to the west;
Steeles Avenue
Steeles Avenue is an east–west street that forms the northern city limit of Toronto and the southern limit of Regional Municipality of York, York Region in Ontario, Canada. It stretches across the western and central Greater Toronto Area from ...
to the north; and the
Rouge River and the Scarborough–Pickering Townline to the east. In addition to Etobicoke Creek and the Rouge River, the city is trisected by two minor rivers and their tributaries, the
Humber River in the west end and the
Don River
The Don ( rus, Дон, p=don) is the fifth-longest river in Europe. Flowing from Central Russia to the Sea of Azov in Southern Russia, it is one of Russia's largest rivers and played an important role for traders from the Byzantine Empire.
Its ...
east of downtown. Both flow southward to Lake Ontario at
Humber Bay
Humber Bay is a bay of Lake Ontario south of Toronto, Ontario, Canada. It is located between Ontario Place on the east and Mimico Creek to the west. The bay gives its name to Etobicoke's Humber Bay neighbourhood.
History
Prior to 1809 the bay ...
and
Toronto Harbour
Toronto Harbour or Toronto Bay is a bay on the north shore of Lake Ontario, in Toronto, Ontario, Canada. It is a natural harbour, protected from Lake Ontario waves by the Toronto Islands. Today, the harbour is used primarily for recreational b ...
respectively, which are part of the longer
Waterfront, as well as Etobicoke Creek and the Rouge River.
The concentration and protection of
Toronto's ravines allows for large tracts of densely forested valleys with recreational trails within the city. Approximately 26 to 28 percent of Toronto is covered with over ten million trees, a fairly high percentage within a large city in North America and there are ambitious proposals to double the coverage. Some parts of Toronto, such as
High Park
High Park is a municipal park in Toronto, Ontario, Canada. High Park is a mixed recreational and natural park, with sporting facilities, cultural facilities, educational facilities, gardens, playgrounds and a zoo. One-third of the park remains ...
and the lower Humber River, are located in the northernmost parts of the
Carolinian forest The Carolinian forest refers to a life zone in eastern North America characterized primarily by the predominance of deciduous (broad-leaf) forest. The term "Carolinian", which is most commonly used in Canada, refers to the deciduous forests which ...
zone found in North America.
The shoreline of the former
Lake Iroquois Lake Iroquois can refer to:
*Lake Iroquois (South Dakota)
* Lake Iroquois (Vermont) in Vermont in the United States
* Lake Iroquois, Illinois in Iroquois County in Illinois in the United States
*Glacial Lake Iroquois
Glacial Lake Iroquois was a p ...
is a major east−west geological feature, which was formed at the end of the
Last Glacial Period. In the west end,
Davenport Road
Davenport Road is an east–west arterial road in Toronto, Ontario, Canada. It is believed to follow an old native trail along the foot of the scarp of the old shoreline of glacial Lake Iroquois.
It currently runs from Yonge Street in the eas ...
follows the ancient shoreline with
the steps to
Casa Loma
Casa Loma (improper Spanish for "Hill House") is a Gothic Revival castle-style mansion and garden in midtown Toronto, Ontario, Canada, that is now a historic house museum and landmark. It was constructed from 1911 to 1914 as a residence for fi ...
rising above and downtown skyscrapers clearly visible to the southeast. It merges with the current Lake Ontario shoreline at the
Scarborough Bluffs
The Scarborough Bluffs, also known as The Bluffs, is an escarpment in the Scarborough, Toronto, Scarborough district of Toronto, Ontario, Canada. There are nine parks along the bluffs, with Bluffers Park being the only one with a beach. Formin ...
promontory.
The
Toronto Islands
The Toronto Islands are a chain of 15 small islands in Lake Ontario, south of mainland Toronto, Ontario, Canada.
Comprising the only group of islands in the western part of Lake Ontario, the Toronto Islands are located just offshore from the ...
are the only group of natural islands located on the western shores of Lake Ontario and were formed from the erosion of the Scarborough Bluffs. The Toronto Islands were originally a sand spit until a major storm separated them from the mainland during the 19th century.
Toronto's immediate neighbours are
Mississauga
Mississauga ( ), historically known as Toronto Township, is a city in the Canadian province of Ontario. It is situated on the shores of Lake Ontario in the Regional Municipality of Peel, adjoining the western border of Toronto. With a popul ...
and
Brampton
Brampton ( or ) is a city in the Canadian Provinces and territories of Canada, province of Ontario. Brampton is a city in the Greater Toronto Area (GTA) and is a List of municipalities in Ontario#Lower-tier municipalities, lower-tier municipalit ...
within the
Regional Municipality of Peel
The Regional Municipality of Peel (informally Peel Region or Region of Peel, also formerly Peel County) is a regional municipality in the Greater Toronto Area, Southern Ontario, Canada. It consists of three municipalities to the west and northwes ...
,
Vaughan
Vaughan () (2021 population 323,103) is a city in Ontario, Canada. It is located in the Regional Municipality of York, just north of Toronto. Vaughan was the fastest-growing municipality in Canada between 1996 and 2006 with its population increas ...
and
Markham Markham may refer to:
It may also refer to brand of of clothing which originates from South Africa which saw it's establishment in 1873.
Biology
* Markham's storm-petrel (''Oceanodroma markhami''), a seabird species found in Chile and Colombia
* ...
within the
Regional Municipality of York
The Regional Municipality of York, also called York Region, is a regional municipality in Southern Ontario, Canada, between Lake Simcoe and Toronto. The region was established after the passing of then Bill 102, An Act to Establish The Regional M ...
, and
Pickering within the
Regional Municipality of Durham
The Regional Municipality of Durham (), informally referred to as Durham Region, is a regional municipality in Southern Ontario, Canada. Located east of Toronto and the Regional Municipality of York, Durham forms the east-end of the Greater Toron ...
. The
Greater Toronto Area
The Greater Toronto Area, commonly referred to as the GTA, includes the City of Toronto and the regional municipalities of Durham, Halton, Peel, and York. In total, the region contains 25 urban, suburban, and rural municipalities. The Greater T ...
(GTA) includes the
regional municipalities
A regional municipality (or region) is a type of Canadian municipal government similar to and at the same municipal government level as a county, although the specific structure and servicing responsibilities may vary from place to place. Reg ...
of
Halton, Peel, York and Durham.
The GTA is part of a larger, natural
ecosystem
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
known as the
Greater Toronto Bioregion. This ecosystem is bounded by Lake Ontario, the
Niagara Escarpment
The Niagara Escarpment is a long escarpment, or cuesta, in Canada and the United States that runs predominantly east–west from New York through Ontario, Michigan, Wisconsin, and into Illinois. The escarpment is most famous as the cliff over ...
, and the
Oak Ridges Moraine
The Oak Ridges Moraine is an ecologically important geological landform in the Mixedwood Plains of south-central Ontario, Canada. The moraine covers a geographic area of between Caledon and Rice Lake, near Peterborough. One of the most signif ...
, and includes many
watersheds that drain into Lake Ontario.
In March 2005, the
Government of Ontario
The government of Ontario (french: Gouvernement de l'Ontario) is the body responsible for the administration of the Canadian province of Ontario. A constitutional monarchy, the Crown—represented in the province by the lieutenant governor†...
unveiled the boundaries of a
greenbelt around the Greater Toronto Area, a area stretching from
Niagara Falls
Niagara Falls () is a group of three waterfalls at the southern end of Niagara Gorge, spanning the border between the province of Ontario in Canada and the state of New York in the United States. The largest of the three is Horseshoe Falls, ...
to
Peterborough
Peterborough () is a cathedral city in Cambridgeshire, east of England. It is the largest part of the City of Peterborough unitary authority district (which covers a larger area than Peterborough itself). It was part of Northamptonshire until ...
. The
green belt
A green belt is a policy and land-use zone designation used in land-use planning to retain areas of largely undeveloped, wild, or agricultural land surrounding or neighboring urban areas. Similar concepts are greenways or green wedges, which hav ...
is designed to curb
urban sprawl
Urban sprawl (also known as suburban sprawl or urban encroachment) is defined as "the spreading of urban developments (such as houses and shopping centers) on undeveloped land near a city." Urban sprawl has been described as the unrestricted growt ...
and to preserve valuable natural areas and
farmland
Agricultural land is typically land ''devoted to'' agriculture, the systematic and controlled use of other forms of lifeparticularly the rearing of livestock and production of cropsto produce food for humans. It is generally synonymous with bot ...
surrounding the city. However, some types of development including detached single residential, quarries and commercial facilities continue to get approved, exerting pressure and population growth on the Greenbelt. Toronto is among the latest in a line of cities that have implemented
growth boundaries of some kind as a method of restricting urban growth, including
Ottawa
Ottawa (, ; Canadian French: ) is the capital city of Canada. It is located at the confluence of the Ottawa River and the Rideau River in the southern portion of the province of Ontario. Ottawa borders Gatineau, Quebec, and forms the core ...
;
Portland, Oregon
Portland (, ) is a port city in the Pacific Northwest and the largest city in the U.S. state of Oregon. Situated at the confluence of the Willamette and Columbia rivers, Portland is the county seat of Multnomah County, the most populous co ...
;
Frankfurt
Frankfurt, officially Frankfurt am Main (; Hessian: , "Frank ford on the Main"), is the most populous city in the German state of Hesse. Its 791,000 inhabitants as of 2022 make it the fifth-most populous city in Germany. Located on its na ...
;
Melbourne
Melbourne ( ; Boonwurrung/Woiwurrung: ''Narrm'' or ''Naarm'') is the capital and most populous city of the Australian state of Victoria, and the second-most populous city in both Australia and Oceania. Its name generally refers to a met ...
;
Seoul
Seoul (; ; ), officially known as the Seoul Special City, is the capital and largest metropolis of South Korea.Before 1972, Seoul was the ''de jure'' capital of the Democratic People's Republic of Korea (North Korea) as stated iArticle 103 ...
and
London
London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a majo ...
.
Climate
Toronto's
continental climate
Continental climates often have a significant annual variation in temperature (warm summers and cold winters). They tend to occur in the middle latitudes (40 to 55 north), within large landmasses where prevailing winds blow overland bringing som ...
is moderated by Lake Ontario; its climate is among the mildest in Canada east of the
Rocky Mountains
The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico in ...
, given Toronto's southerly latitude within the country. Downtown Toronto sits in a pocket of the humid continental climate (
Köppen climate classification
The Köppen climate classification is one of the most widely used climate classification systems. It was first published by German-Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, notabl ...
''Dfa'') zone found at the southwestern end of Lake Ontario covering the southern part of the city — including downtown (but excluding the
Toronto Islands
The Toronto Islands are a chain of 15 small islands in Lake Ontario, south of mainland Toronto, Ontario, Canada.
Comprising the only group of islands in the western part of Lake Ontario, the Toronto Islands are located just offshore from the ...
), where the annual average temperature exceeds . Some of Toronto, outside of
the pre-1998 city limits, some suburban areas, and the Toronto Islands, fall within the ''Dfb'' climate regimen. This difference partly results from the
urban heat island
An urban heat island (UHI) is an urban or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. The temperature difference is usually larger at night than during the day, and is most apparen ...
effect. Toronto is located in
hardiness zone
A hardiness zone is a geographic area defined as having a certain average annual minimum temperature, a factor relevant to the survival of many plants. In some systems other statistics are included in the calculations. The original and most wide ...
7a, with decreasing hardiness further away from the downtown core (5b in the suburbs).
There is a high degree of variability from year to year and sometimes over a period of days, particularly during the
winter
Winter is the coldest season of the year in polar and temperate climates. It occurs after autumn and before spring. The tilt of Earth's axis causes seasons; winter occurs when a hemisphere is oriented away from the Sun. Different cultures ...
months.
![Downtown from Ward's Island (11741567236)](https://upload.wikimedia.org/wikipedia/commons/4/4e/Downtown_from_Ward%27s_Island_%2811741567236%29.jpg)
Lake Ontario's water temperature varies due to
upwelling
Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water from deep water towards the ocean surface. It replaces the warmer and usually nutrient-depleted surface water. The nutr ...
of colder water or warmer pools of
surface water
Surface water is water located on top of land forming terrestrial (inland) waterbodies, and may also be referred to as ''blue water'', opposed to the seawater and waterbodies like the ocean.
The vast majority of surface water is produced by prec ...
creating very localized thermal contrast; the deeper waters of the lake, far from the shore, remain at a near-constant water temperature of , the effect of which is either cooling or warming (in winter). This creates generally warmer nights through the colder season than would otherwise occur. When offshore winds blow in summer, they warm as they near the lakeshore in the evening; conversely, the cooling effect by the lake is most pronounced on
spring
Spring(s) may refer to:
Common uses
* Spring (season), a season of the year
* Spring (device), a mechanical device that stores energy
* Spring (hydrology), a natural source of water
* Spring (mathematics), a geometric surface in the shape of a ...
afternoons, which can affect Toronto even more than other cities on the Great Lakes due its exposure to onshore winds from the east to southeast, on some days, the temperatures can be as much as cooler than areas far removed from Lake Ontario, an effect that wanes by summer when the dominant windflow becomes more southwesterly and the lake surface temperature warms.
Springs and
autumn
Autumn, also known as fall in American English and Canadian English, is one of the four temperate seasons on Earth. Outside the tropics, autumn marks the transition from summer to winter, in September ( Northern Hemisphere) or March ( Sou ...
s are shorter seasons than summers and winters, and they feature varied weather with alternating periods of dry, sunny weather and rain. Many days in these seasons are sunny with pleasant rather than warm or cold temperatures. Nights are generally cool, but frosts are rare. Snow can fall in early spring or late fall but usually melt quickly after contact with the ground. At these changeable times of the year, temperature contrasts (up to in extreme cases) can occur within a short time frames due to rapidly changing air masses that sweep across the continent, often accompanied by high winds. Due to these airmass changes, temperatures of or above have been recorded as early as April 16 and as late as October 8. Conversely, temperatures of or below at night have been recorded as early as November 6 and as late as April 18. Snowfall has been reported as early as October 1 and as late as May 28. Toronto's weather is affected by the relative position of the polar
jet stream
Jet streams are fast flowing, narrow, meandering thermal wind, air currents in the Atmosphere of Earth, atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are west ...
and continental storm track, both of which pass over or near to the area with some frequency. This is determined by a number of complex global weather drivers, such as
ENSO,
NOA/
AO Oscillations and the
Polar vortex
A circumpolar vortex, or simply polar vortex, is a large region of cold, rotating air that encircles both of Earth's polar regions. Polar vortices also exist on other rotating, low-obliquity planetary bodies. The term polar vortex can be used to ...
.
There is no "dry season" as precipitation falls in all months with regularity (but mainly snow during the winter), but summer rains result mostly from thunderstorms, which make for higher average amounts as a general rule with occasional dry periods. February and March rank as the driest months on average. Annual average
precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
is .
Cherry blossom trees bloom in Toronto during late April and early May.
Winter and snowfall
![April 2018 ice storm in Toronto6](https://upload.wikimedia.org/wikipedia/commons/c/c0/April_2018_ice_storm_in_Toronto6.jpg)
Despite being cold, extended snow-free periods occur in most winter seasons and precipitation can fall as rain with temperatures sometimes climbing above . Average winter snowfall is at the weather station in
Downtown Toronto
Downtown Toronto is the main central business district of Toronto, Ontario, Canada. Located entirely within the district of Old Toronto, it is approximately 16.6 square kilometres in area, bounded by Bloor Street to the northeast and Dupont Stre ...
[
] and at
Toronto Pearson International Airport
Lester B. Pearson International Airport , commonly known as Toronto Pearson International Airport, is an international airport located in Mississauga, Ontario, Canada. It is the main airport serving Toronto, its metropolitan area, and the surro ...
.
The average January maximum / minimum is between in the city.
There are usually a few colder periods where temperatures remain below and less frequently below at night (especially in the northern suburbs), with
wind chill
Wind chill or windchill (popularly wind chill factor) is the lowering of body temperature due to the passing-flow of lower-temperature air.
Wind chill numbers are always lower than the air temperature for values where the formula is valid. When ...
s making it feel like .
Due to its position on the northwest shore of Lake Ontario, Toronto is not a direct target of heavy, wind−whipped
lake-effect snow
Lake-effect snow is produced during cooler atmospheric conditions when a cold air mass moves across long expanses of warmer lake water. The lower layer of air, heated up by the lake water, picks up water vapor from the lake and rises up through ...
squall
A squall is a sudden, sharp increase in wind speed lasting minutes, as opposed to a wind gust, which lasts for only seconds. They are usually associated with active weather, such as rain showers, thunderstorms, or heavy snow. Squalls refer to the ...
s that hit other
Great Lake cities on the south/east shorelines of the lakes, in areas where prevailing winds amplify lake effect. Despite this, there are usually two or more heavy snowfalls each winter which deposit at least accumulation, usually from powerful
winter storm
A winter storm is an event in which wind coincides with varieties of precipitation that only occur at freezing temperatures, such as snow, mixed snow and rain, or freezing rain. In temperate continental climates, these storms are not necessar ...
s known as Alberta clippers, "
Colorado Lows" or
panhandle hook A panhandle hook (also called a pan handle hook or Texas hooker) is a relatively infrequent winter storm system whose cyclogenesis occurs in the South to southwestern United States from the late fall through winter and into the early spring months ...
s that pick up moisture en route to the Great Lakes. These storms can produce strong easterly driven winds that fetch additional
moisture
Moisture is the presence of a liquid, especially water, often in trace amounts. Small amounts of water may be found, for example, in the air (humidity), in foods, and in some commercial products. Moisture also refers to the amount of water vapo ...
from Lake Ontario. They frequently come with a volatile mix of snow,
ice pellets
Ice pellets are a form of precipitation consisting of small, hard, translucent balls of ice. Ice pellets are different from graupel ("soft hail") which is made of frosty white opaque rime, and from a mixture of rain and snow which is a slushy ...
,
freezing rain
Freezing rain is rain maintained at temperatures below freezing by the ambient air mass that causes freezing on contact with surfaces. Unlike a mixture of rain and snow or ice pellets, freezing rain is made entirely of liquid droplets. The raind ...
and sometimes just ordinary rain, all of which can disrupt transportation, and in severe cases, interrupt power supply. A
sustained freezing rain event occurred on December 22, 2013, plunging 30 percent of the city into darkness, some until after Christmas Day.
![The City of Toronto snowplough](https://upload.wikimedia.org/wikipedia/commons/1/13/The_City_of_Toronto_snowplough.jpg)
Such storms can also produce large snowfall amounts, higher totals found in areas closer to Lake Ontario, sometimes falling over a series of days or weeks creating havoc. On January 13, 1999, after
a series of snowstorms, then-Toronto mayor
Mel Lastman
Melvin Douglas Lastman (March 9, 1933 – December 11, 2021) was a Canadian businessman and politician who served as the third mayor of North York from 1973 to 1997 and 62nd mayor of Toronto from 1998 to 2003. He was the first person to serve ...
called in the
Canadian Armed Forces
}
The Canadian Armed Forces (CAF; french: Forces armées canadiennes, ''FAC'') are the unified military forces of Canada, including sea, land, and air elements referred to as the Royal Canadian Navy, Canadian Army, and Royal Canadian Air Force.
...
to assist with snow removal and clearing streets. Within twelve days, the downtown Toronto weather station at the
University of Toronto
The University of Toronto (UToronto or U of T) is a public research university in Toronto, Ontario, Canada, located on the grounds that surround Queen's Park. It was founded by royal charter in 1827 as King's College, the first institution ...
(
Trinity College Trinity College may refer to:
Australia
* Trinity Anglican College, an Anglican coeducational primary and secondary school in , New South Wales
* Trinity Catholic College, Auburn, a coeducational school in the inner-western suburbs of Sydney, New ...
near
Queen's Park) recorded an average season's worth of of snow, much of it lake effect from Lake Ontario and a monthly record for January, but fell short of the snowiest month overall March 1870, with , of which fell over a 5-day span. February 2008 set a record a snowfall record for the month with falling at the airport. The winter of 2007–08 brought accumulated seasonal snowfall totals of downtown and at the airport. The heavy winter snows, in combination with record rains during June–July of that year made 2008 the wettest year on the climate record with over of total precipitation. The largest single snowstorm on record took place on December 11–12, 1944, when accumulated, with on December 11 alone.
On the opposite extreme, the winter of 2011–12 had the lowest seasonal snowfall total with only . March 2012 was the warmest March on record. The least snowfall in a calendar year was 2006, with only . The El Niño influenced winter of 2009–10 had , March 2010 recorded no measurable snow, the first such occurrence in any March since 1946, and was followed by the warmest April ever on record.
Winter weather conditions in Toronto can vary greatly from one year to another and is significantly affected by global weather patterns such as
El Niño–Southern Oscillation
El Niño–Southern Oscillation (ENSO) is an irregular periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean, affecting the climate of much of the tropics and subtropics. The warming phase of the sea te ...
(ENSO).
El Niño
El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date L ...
winters are generally mild and dry, with decreased snowfall (such as the winters of 2009–2010 and 2015–2016), while
La Niña
La Niña (; ) is an oceanic and atmospheric phenomenon that is the colder counterpart of as part of the broader El Niño–Southern Oscillation (ENSO) climate pattern. The name ''La Niña'' originates from Spanish for "the girl", by an ...
winters tend have more precipitation (the aforementioned winters of 1999 and 2008 are both La Niña). ENSO Neutral years are more unpredictable.
Summer
![Boating in the Toronto Islands](https://upload.wikimedia.org/wikipedia/commons/1/1c/Boating_in_the_Toronto_Islands.jpg)
Maximum temperatures typically range from with moderate to high humidity, proximity to Lake Ontario and the other lakes contribute to summer humidity but far away sources like the Gulf of Mexico also factor in. The subtropical jet can move well north of the area in the midsummer influenced largely by the strength and position of the
Bermuda-Azores High
The Azores High also known as North Atlantic (Subtropical) High/Anticyclone or the Bermuda-Azores High, is a large subtropical semi-permanent centre of high atmospheric pressure typically found south of the Azores in the Atlantic Ocean, at the Ho ...
and ridging over the North American continent, in some summers, it is a dominating influence.
Lake effect cooling varies greatly depending on location within the city and strength and direction of localized winds, variation in water temperature and currents due to recent weather, the most pronounced effect on the
Toronto Islands
The Toronto Islands are a chain of 15 small islands in Lake Ontario, south of mainland Toronto, Ontario, Canada.
Comprising the only group of islands in the western part of Lake Ontario, the Toronto Islands are located just offshore from the ...
and immediate lakeshore especially around the
Scarborough Bluffs
The Scarborough Bluffs, also known as The Bluffs, is an escarpment in the Scarborough, Toronto, Scarborough district of Toronto, Ontario, Canada. There are nine parks along the bluffs, with Bluffers Park being the only one with a beach. Formin ...
, hence the term "cooler by the lake". This is less a factor in the west and northwest parts of the city. Temperatures over occur on average seven days each year (three consecutive days of such temperatures is defined as a
heat wave
A heat wave, or heatwave, is a period of excessively hot weather, which may be accompanied by high humidity, especially in oceanic climate countries. While definitions vary, a heat wave is usually measured relative to the usual climate in the ...
, which occur in most summers but maximums rarely exceed , which last occurred on July 21, 2011). However, coupled with high humidity, the
humidex
The humidex (short for humidity index) is an index number used by Canadian meteorologists to describe how hot the weather feels to the average person, by combining the effect of heat and humidity. The term ''humidex'' was coined in 1965. The humid ...
value can rise well above during these heat events, creating great discomfort. Nighttime temperatures generally hover close to in the city but during hotter spells remain closer to . Summer heat episodes are usually broken by cooler, drier periods that can be brief.
Thunderstorms are also a regular occurrence and can pop up quickly, especially west and north of the city in areas more prone to the "lake breeze front" or "lake breeze thunderstorms" phenomenon, in which intense, sharply defined squall lines develop quickly on summer afternoons inland, amplified by localized variation in wind patterns between the Great Lakes. These storms sometimes, but not always move into the city causing localized flooding resulting from downpours with high rainfall amounts, intense lightning but less often severe winds knocking down trees and powerlines.
Severe weather and records
In addition to snowstorms, ice storms, windstorms, heavy rainfall events associated with
tropical storms
A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dependi ...
or very severe
thunderstorm
A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are someti ...
s,
tornado
A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, altho ...
es are rare but do occur, particularly in the northern and western suburbs. That area sits in a "
tornado alley
Tornado Alley is a loosely defined area of the central United States where tornadoes are most frequent. The term was first used in 1952 as the title of a research project to study severe weather in areas of Texas, Louisiana, Oklahoma, Kansas, So ...
" where tornadoes occur the most often in Canada. Downtown Toronto, on the other hand, is generally shielded from tornadic storms by the lake shadow resulting from the lake breezes. Tornado warnings have been posted for the city on a few occasions in the early 21st century, however,
no touchdowns have been confirmed within city limits since a weak tornado hit
Scarborough Scarborough or Scarboro may refer to:
People
* Scarborough (surname)
* Earl of Scarbrough
Places Australia
* Scarborough, Western Australia, suburb of Perth
* Scarborough, New South Wales, suburb of Wollongong
* Scarborough, Queensland, su ...
in 1998. A pair of dangerous
F2 tornados did touchdown in neighbouring
Vaughan
Vaughan () (2021 population 323,103) is a city in Ontario, Canada. It is located in the Regional Municipality of York, just north of Toronto. Vaughan was the fastest-growing municipality in Canada between 1996 and 2006 with its population increas ...
during
a tornado outbreak on August 20, 2009.
A powerful derecho touched down on May 21, 2022.
Toronto is susceptible to
flash flood
A flash flood is a rapid flooding of low-lying areas: washes, rivers, dry lakes and depressions. It may be caused by heavy rain associated with a severe thunderstorm, hurricane, or tropical storm, or by meltwater from ice or snow flowing o ...
ing due to its various
ravines and valleys that can easily flood, as well as generally poor drainage due to its large urban area. Flooding can result from remnants of tropical storms, heavy rainfall combined with snowmelt, or summertime thunderstorms stalled out along lake breeze boundaries. Low-lying areas, such as the lower reaches of the
Don River
The Don ( rus, Дон, p=don) is the fifth-longest river in Europe. Flowing from Central Russia to the Sea of Azov in Southern Russia, it is one of Russia's largest rivers and played an important role for traders from the Byzantine Empire.
Its ...
valley, are the most likely to flood. This often leads to the shutdown of the
Don Valley Parkway
The Don Valley Parkway (DVP) is a municipal expressway in Toronto, Ontario, Canada, which connects the Gardiner Expressway in downtown Toronto with Highway 401. North of Highway 401, it continues as Highway 404. The parkway run ...
and
GO Transit
GO Transit is a regional public transit system serving the Greater Golden Horseshoe region of Ontario, Canada. With its hub at Union Station in Toronto, GO Transit's green-and-white trains and buses serve a population of more than seven millio ...
's
Richmond Hill line
Richmond Hill is one of the seven train lines of the GO Transit system in the Greater Toronto Area, Ontario, Canada. It operates between Union Station in Toronto to Bloomington GO Station in the north in Richmond Hill. Trains on the line operat ...
. A second mouth is being built for the Don River to mitigate flooding, creating
Villiers Island
Villiers Island is a area in Toronto's Port Lands being converted to an island. The project is a part of Port Lands Flood Protection Project by Waterfront Toronto. To prevent flooding from the Don River, a channel is being created to extend th ...
.
![Hurricane Hazel -- Weston Golf Club](https://upload.wikimedia.org/wikipedia/commons/a/a5/Hurricane_Hazel_--_Weston_Golf_Club.jpg)
The tropical storm remnant of
Hurricane Hazel
Hurricane Hazel was the deadliest, second costliest, and most intense hurricane of the 1954 Atlantic hurricane season. The storm killed at least 469 people in Haiti before striking the United States near the border between North and South ...
caused 81 deaths in October 1954 due to flooding that swept homes along river banks into Lake Ontario. A sudden
downburst
In meteorology, a downburst is a strong downward and outward gushing wind system that emanates from a point source above and blows radially, that is, in straight lines in all directions from the area of impact at surface level. Capable of pro ...
during a strong thunderstorm was believed to have played a contributing factor in the
Air France Flight 358
Air France Flight 358 was a regularly scheduled international flight from Charles de Gaulle Airport in Paris, France, to Toronto Pearson International Airport in Ontario, Canada. On the afternoon of 2 August 2005, while landing at Pearson Airpo ...
crash on August 2, 2005. Just a few weeks later on August 19, part of
a tornado outbreak in Southern Ontario, record-breaking intense rainfall, the worst since Hazel, deluged north-central sections of the city within a couple of hours and destroying a section of
Finch Avenue West
Finch Avenue is an arterial road, arterial thoroughfare that travels east–west in Toronto, Ontario, Canada. The road continues west into the Regional Municipality of Peel as List of numbered roads in Peel Region, Regional Road 2 and east in ...
in North York resulting in record insurance claims. Some rain gauges recorded of rain, over in just one hour. Another large rainstorm with intense, record rainfall amounts struck a wide swath of the city during the afternoon rush hour on July 8, 2013 flooding city streets, subway tunnels, basements and knocking out power for over two million residents, stranding commuters, some having to be rescued from a submerged train. A daily rainfall record of was set at Pearson Airport, most falling in an hour and a half. Flood insurance claims are likely to exceed the 2005 storm due to a wider area affected. In the springs of 2017 and 2019, heavy rain combined with snowmelt led to the water levels of
Lake Ontario
Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north, west, and southwest by the Canadian province of Ontario, and on the south and east by the U.S. state of New York. The Canada–United States border sp ...
to rise to record levels, flooding parts of the
Toronto Islands
The Toronto Islands are a chain of 15 small islands in Lake Ontario, south of mainland Toronto, Ontario, Canada.
Comprising the only group of islands in the western part of Lake Ontario, the Toronto Islands are located just offshore from the ...
and closing it to the public.
The most severe heat wave in Toronto occurred in 1936, during the
1936 North American heat wave
The 1936 North American heat wave was one of the most severe heat waves in the modern history of North America. It took place in the middle of the Great Depression and Dust Bowl of the 1930s and caused catastrophic human suffering and an enormous ...
, when downtown temperatures in Toronto exceeded on three consecutive days (July 8 – 10), with nighttime temperatures not falling below . The city was ill-equipped at that time to handle such a prolonged extreme
heat wave
A heat wave, or heatwave, is a period of excessively hot weather, which may be accompanied by high humidity, especially in oceanic climate countries. While definitions vary, a heat wave is usually measured relative to the usual climate in the ...
, and
heat stroke
Heat stroke or heatstroke, also known as sun stroke, is a severe heat illness that results in a body temperature greater than , along with red skin, headache, dizziness, and confusion. Sweating is generally present in exertional heatstroke, ...
claimed 225 lives in the city, not counting indirect deaths from causes such as drowning. The hottest month recorded, however, was July 1921, when the average maximum temperature downtown was , with a monthly mean temperature of , this was equalled in July 2020. At Toronto Pearson International Airport, the highest monthly maximum average was in July 1955, however the highest mean of was set in July 2020, records there began in 1937.
The highest
humidex
The humidex (short for humidity index) is an index number used by Canadian meteorologists to describe how hot the weather feels to the average person, by combining the effect of heat and humidity. The term ''humidex'' was coined in 1965. The humid ...
(combined feel of temperature and humidity) reached at the airport during the
heat wave of July 1995, downtown it reached on July 21, 2011 during the
2011 North American heat wave
The 2011 North American heat wave was a deadly summer 2011 heat wave that affected the South Central United States, Southern Plains, the Midwestern United States, Eastern Canada, the Northeastern United States, and much of the East Coast of the Un ...
.
The coldest minimum temperature of was recorded on January 10, 1859. The coldest temperature recorded at the airport was on January 4, 1981, and the coldest windchill recorded was on the same day.
The coldest month overall was at the airport in
February 2015 and at downtown in February 1875. Other notable cold waves occurred in January 1994 and February 1934. Winter cold snaps pose a danger as they often come with high winds, leaving the city's homeless population very prone to
frostbite
Frostbite is a skin injury that occurs when exposed to extreme low temperatures, causing the freezing of the skin or other tissues, commonly affecting the fingers, toes, nose, ears, cheeks and chin areas. Most often, frostbite occurs in the han ...
and
hypothermia
Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe h ...
.
Upward temperature trend
Based on public records provided by Environment Canada, the average annual temperature has increased at Pearson Airport over a period of 30 years. If compared with the thirty-year normals from 1971 to 2000, more of this increase occurred at night: the average minimum temperature has been higher. Average precipitation during the same period was close to the average of the previous period, snowfall totals down only marginally with slightly higher rainfall. In order from the top: December, September, July and January have seen the highest average temperature increases. Part of this warming is likely attributed to
increased urban growth surrounding the airport.
An older study conducted in the 1990s analysed the heat island effect comparing data from selected regional stations, including both Downtown Toronto and Pearson Airport, enough for Downtown Toronto to have a different
Köppen climate classification
The Köppen climate classification is one of the most widely used climate classification systems. It was first published by German-Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, notabl ...
from its surrounding area.
Statistics
Topography
Toronto has numerous hills and valleys that were carved out during the
last Ice Age. The ravines are largely undeveloped, primarily as the result of
Hurricane Hazel
Hurricane Hazel was the deadliest, second costliest, and most intense hurricane of the 1954 Atlantic hurricane season. The storm killed at least 469 people in Haiti before striking the United States near the border between North and South ...
in 1954.
A significant topographical feature is the old shoreline of the
Glacial Lake Iroquois
Glacial Lake Iroquois was a prehistoric proglacial lake that existed at the end of the last ice age approximately 13,000 years ago.
The lake was essentially an enlargement of the present Lake Ontario that formed because the St. Lawrence River down ...
, known as the Iroquois Plain. The plain consists mostly of sand deposits and eroded shale and gently slopes about north from Lake Ontario. The Iroquois Plain joins Lake Ontario at the
Scarborough Bluffs
The Scarborough Bluffs, also known as The Bluffs, is an escarpment in the Scarborough, Toronto, Scarborough district of Toronto, Ontario, Canada. There are nine parks along the bluffs, with Bluffers Park being the only one with a beach. Formin ...
where erosion and the currents of Lake Ontario have carried sand deposits into
Toronto Harbour
Toronto Harbour or Toronto Bay is a bay on the north shore of Lake Ontario, in Toronto, Ontario, Canada. It is a natural harbour, protected from Lake Ontario waves by the Toronto Islands. Today, the harbour is used primarily for recreational b ...
to form the Toronto Islands. Above the Iroquois Plain, the topography includes two features: the South Slope and the Peel Plain. The South Slope is the southern part of an interlobular moraine the
Oak Ridges Moraine
The Oak Ridges Moraine is an ecologically important geological landform in the Mixedwood Plains of south-central Ontario, Canada. The moraine covers a geographic area of between Caledon and Rice Lake, near Peterborough. One of the most signif ...
. The South Slope has a gentle slope as well, and experiences relatively high runoff as water infiltration is relatively low. The Peel Plain is mostly clay and generally flatter than the South Slope. Water infiltration is also low. Historically, the Peel Plain and South Slope were considered to be high-quality agricultural lands, unlike the Iroquois Plain, which is very sandy. These areas are now heavily urbanized.
Both
Dufferin Street
Dufferin Street is a major north–south street in Toronto, Vaughan and King, Ontario, Canada. It is a concession road, two concessions (4 km) west of Yonge Street. The street starts at Exhibition Place, continues north to Toronto's northe ...
and Caledonia Road between
Davenport Road
Davenport Road is an east–west arterial road in Toronto, Ontario, Canada. It is believed to follow an old native trail along the foot of the scarp of the old shoreline of glacial Lake Iroquois.
It currently runs from Yonge Street in the eas ...
and
Eglinton Avenue
Eglinton Avenue is a major east–west arterial thoroughfare in Toronto and Mississauga in the Canadian province of Ontario. The street begins at Highway 407 (but does not interchange with the tollway) at the western limits of Mississauga, as a ...
, in the
York district, run across numerous steep hills and valleys and the neighbourhood in this area is named
Fairbank. Fairbank and
Silverthorn Silverthorn may refer to:
* ''Silverthorn'' (album), an album by Kamelot
* ''Silverthorn'' (novel), a novel by Raymond E. Feist
*Silverthorn, Toronto, a neighbourhood in Toronto
*Silverthorn Collegiate Institute
*Silverthorn, a character on ''The ...
to the west have often been compared with
the many hills that make up San Francisco.
However, parts of the hills and valleys are slightly levelled for
GO Transit
GO Transit is a regional public transit system serving the Greater Golden Horseshoe region of Ontario, Canada. With its hub at Union Station in Toronto, GO Transit's green-and-white trains and buses serve a population of more than seven millio ...
's
Barrie line
Barrie is one of the seven train lines of the GO Transit system in the Greater Toronto Area, Ontario, Canada. It extends from Union Station in Toronto in a generally northward direction to Barrie, and includes ten stations along its route. From ...
that runs through this area.
Vaughan Road
Vaughan Road is a road in Toronto, Ontario, Canada. It is a contour collector road that is parallel to a Subterranean river, buried Urban stream, creek to the north called Castle Frank Brook. Vaughan Road begins on Bathurst Street (Toronto), Bathu ...
runs parallel to the buried
Castle Frank Brook
Castle Frank Brook is a Subterranean river, buried Urban stream, creek and south-west flowing tributary of the Don River (Ontario), Don River in central and north-western Toronto, Ontario, originating near the intersection of Lawrence Avenue and D ...
to the northeast.
The
Don River
The Don ( rus, Дон, p=don) is the fifth-longest river in Europe. Flowing from Central Russia to the Sea of Azov in Southern Russia, it is one of Russia's largest rivers and played an important role for traders from the Byzantine Empire.
Its ...
is categorized as an
underfit river, given that the river is too small for its much wider and deeper valley. The same is true for the
Humber River, the
Rouge River, and
the various smaller waterways of Toronto.
Grenadier Pond in
High Park
High Park is a municipal park in Toronto, Ontario, Canada. High Park is a mixed recreational and natural park, with sporting facilities, cultural facilities, educational facilities, gardens, playgrounds and a zoo. One-third of the park remains ...
is the largest body of water fully within Toronto's city limits. During the winter, it becomes a natural skating rink.
See also
*
Fauna of Toronto
The fauna of Toronto include a variety of different species situated within the city limits. Toronto contains a mosaic of ecosystems that includes forests, rivers, streams, and wetlands, which allows it to support a large variety of fauna. Approx ...
*
List of Toronto parks
The following is a list of the parks in the city of Toronto, Ontario, Canada. The appearance of Toronto ravine system, Toronto's ravines was altered by floods caused by Hurricane Hazel in October 1954 and many of Toronto's parks were established i ...
*
Native trees in Toronto
Native trees in Toronto are trees that are naturally growing in Toronto and were not later introduced by humans. The area that presently comprise Toronto is a part of the Carolinian forest, although agricultural and urban developments destroyed sig ...
*
Toronto waterway system
The Toronto waterway system comprises a series of natural and man-made watercourses in the Canadian city of Toronto. The city is dominated by a large river system spanning most of the city including the Don River, Etobicoke Creek, Highland Creek, ...
Notes
References
{{DEFAULTSORT:Geography Of Toronto