View source for Geography of Ontario

{{Short description|none}} <!-- This short description is INTENTIONALLY "none" - please see WP:SDNONE before you consider changing it! -->
{{Use Canadian English|date=January 2024}}
{{Use dmy dates|date=January 2024}}
{{Country geography <!-- Adapted for Province use -->
|name            = Ontario
|map             = Map_ont.jpg
|continent       = [[North America]]
|region          = [[Eastern Canada]]<br/>[[Central Canada]]
|coordinates     = {{Coord|49|15|0|N|84|29|59|W}}
|km area         = 1076395
|percent land    = 85.3
|km coastline    = 3840
|borders         = [[Land borders|Total land borders]]: U.S. states [[Michigan]], [[New York (state)|New York]], [[Minnesota]]; Canadian provinces [[Manitoba]], [[Nunavut]], and [[Quebec]]
|highest point   = [[Ishpatina Ridge]]<br/>{{convert|693|m|ft|abbr=on}}
|lowest point    = [[Hudson Bay]]<br/>sea level
|longest river   = [[Albany River]]<br/>{{convert|980|km|mi|abbr=on}}|largest lake    = [[Lake Superior]]<br/> {{convert|28,700|km2|sqmi|abbr=on}}<br/>(Canadian portion only)
}}

'''[[Ontario]]''' is located in [[Eastern Canada|East]]/[[Central Canada|Central]] Canada. It is Canada's second largest province by land area. Its physical features vary greatly from the [[Mixedwood Plains Ecozone (Canada)|Mixedwood Plains]] in the southeast to the [[Taiga|boreal forests]] and [[tundra]] in the north. Ontario borders Manitoba to the west, [[Hudson Bay]] and [[James Bay]] to the north, [[Quebec]] to the east, and the [[Great Lakes]] and the [[United States]] to the south. The province is named for Great [[Lake Ontario]], an adaptation of the [[Iroquois]] word ''Onitariio'', meaning "beautiful lake", or ''Kanadario'', variously translated as "beautiful water". There are approximately 250,000 lakes and over {{convert|100,000|km|mi}} of rivers in the province.

Almost 94% of the population is concentrated within [[Southern Ontario]], where the population was over 12,850,000 in the 2011 census. The [[Golden Horseshoe]] is the most populous part of Southern Ontario, with a population of 9,765,188 in the 2021 census.<ref name="GHpopulation">[http://geodepot.statcan.ca/Diss/Maps/ThematicMaps/horseshoe_e.cfm The population of communities in the Golden Horseshoe.] {{webarchive|url=https://web.archive.org/web/20061208012153/http://geodepot.statcan.ca/Diss/Maps/ThematicMaps/horseshoe_e.cfm |date=2006-12-08 }}</ref>

==Population==
[[File:Cntower2.jpg|250px|right|thumb|The [[Toronto]] skyline seen from [[Toronto Harbour]]]]
Ontario is the most populous province in Canada. [[Southern Ontario]] is one of the densest regions in the country. [[Northern Ontario|The north]] is vast and sparse compared to the south. The national capital [[Ottawa]] is located in Ontario bordering Quebec. Located within the [[Golden Horseshoe]], [[Toronto]] is the capital of Ontario, the financial centre of Canada, and the country's most populous city.

Ontario is the second-most [[Urbanization|urbanized]] province after [[British Columbia]], with 85.9% of the population living in urban areas.<ref>{{Cite web |url=http://www12.statcan.ca/census-recensement/2011/as-sa/98-310-x/98-310-x2011003_2-eng.cfm |title=Canada's rural population since 1851 |access-date=17 February 2012 |archive-date=13 February 2012 |archive-url=https://web.archive.org/web/20120213072214/http://www12.statcan.ca/census-recensement/2011/as-sa/98-310-x/98-310-x2011003_2-eng.cfm |url-status=dead }}</ref>

{| class="wikitable"
|+ Population by Statistical Area Classification<ref>[http://www12.statcan.ca/census-recensement/2011/dp-pd/hlt-fst/pd-pl/Table-Tableau.cfm?LANG=Eng&TABID=1&T=601&SR=1&RPP=25&S=0&O=D&CMA=0&PR=35#C2 Population and dwelling counts, for Canada, provinces and territories by the Statistical Area Classification, 2011 and 2006 censuses]</ref>
|-
! rowspan = "2" |Statistical Area Classification
! colspan = "2" | 2011 Census
! colspan = "2" | 2006 Census
! rowspan = "2" | Change
|-
! Population
! % of total
! Population
! % of total
|-
|Within CMAs  ||10,270,006 ||79.9% ||9,591,529 ||78.9% || {{profit}}7.1%
|-
|Within CAs  ||1,133,127 ||8.8% ||1,128,614 ||9.3% || {{profit}}0.4%
|- style="background: lightblue" 
| '''Total CMA/CA'''  ||11,403,133 ||88.7% ||10,720,143 ||88.2% || {{profit}}6.4%
|-
|Strongly influenced  ||644,299 ||5.0% ||631,410 ||5.2% || {{profit}}2.0%
|-
|Moderately influenced  ||555,931 ||4.3% ||554,062 ||4.5% || {{profit}}0.3%
|-
|Weakly influenced  ||225,197 ||1.8% ||232,107 ||1.9% || {{loss}}3.0%
|-
|Not influenced  ||23,261 ||0.2% ||22,560 ||0.2% || {{profit}}3.1%
|-  style="background: lightblue" 
|'''Outside CMA/CA'''  ||1,448,688 ||11.3% ||1,440,139 ||11.8% || {{profit}}0.6%
|-
|'''Total'''  ||'''12,851,821''' ||'''100.0%''' ||'''12,160,282''' ||'''100.0%''' ||{{profit}}'''5.7%'''
|}

{| class="wikitable"
|+ Census Metropolitan Areas (CMAs) by population
!City
!2016<ref>{{cite web|url=http://www12.statcan.gc.ca/census-recensement/2016/dp-pd/hlt-fst/pd-pl/Table.cfm?Lang=Eng&T=201&S=3&O=D|title=Population and Dwelling Count Highlight Tables, 2016 Census|website=12.statcan.gc.ca|date=8 February 2017 |access-date=27 May 2018}}</ref>
!2011<ref>{{cite web|url=http://www12.statcan.gc.ca/census-recensement/2011/dp-pd/hlt-fst/pd-pl/Table-Tableau.cfm?LANG=Eng&T=202&PR=35&S=0&O=D&RPP=50|title=Population and dwelling counts, for Canada, provinces and territories, census metropolitan areas and census agglomerations, 2011 and 2006 censuses|website=12.statcan.gc.ca|access-date=27 May 2018}}</ref>
!2006<ref>{{cite web|url=http://www12.statcan.gc.ca/census-recensement/2006/dp-pd/hlt/97-550/Index.cfm?TPL=P1C&Page=RETR&LANG=Eng&T=202&SR=1&S=4&O=D&RPP=50&PR=35|title=Population and dwelling counts, for Canada, provinces and territories, census metropolitan areas and census agglomerations, 2006 and 2001 censuses - 100% data|website=12.statcan.gc.ca|access-date=27 May 2018}}</ref>
!2001<ref>{{cite web|url=http://www12.statcan.gc.ca/english/census01/products/standard/popdwell/Table-CMA-P.cfm?T=1&PR=35&SR=1&S=1&O=A|title=Population and Dwelling Counts, for Canada, Provinces and Territories, Census Metropolitan Areas and Census Agglomerations, 2001 and 1996 Censuses - 100% Data|website=12.statcan.gc.ca|access-date=27 May 2018}}</ref> 
!1996<ref name="statcan.gc.ca">{{cite web|url=http://www.statcan.gc.ca/c1996-r1996/4129975-eng.htm|title=Population and Dwelling Counts, for Census Metropolitan : Areas in Decreasing Order of 1996 Population, 1991 and 1996 Censuses - 100% Data|website=Statcan.gc.ca|access-date=27 May 2018}}</ref>
!1991<ref name="statcan.gc.ca"/>
|-
|[[Toronto]] ||5,928,040|| 5,583,064 ||5,113,149 ||4,682,897 || 4,263,757 || 3,898,933 	
|-
|[[Ottawa]]-[[Gatineau]] ||1,323,783|| 1,236,324 || 1,130,761 ||1,063,664 || 1,010,498 || 941,814
|-
|[[Hamilton, Ontario|Hamilton]] ||747,545|| 721,053 ||692,911 ||662,401 ||624,360 || 599,760
|-
|[[Regional Municipality of Waterloo|Kitchener-Cambridge-Waterloo]] ||523,894|| 477,160 ||451,235 ||414,284||382,940 ||356,421		
|-
|[[London, Ontario|London]] ||494,069|| 474,786 ||457,720 ||432,451 ||398,616 || 381,522
|-
|[[St. Catharines]]-[[Niagara Regional Municipality, Ontario|Niagara]] ||406,074|| 392,184 ||390,317 ||377,009 	||372,406 || 364,552 		
|-
|[[Oshawa]] ||379,848|| 356,177 ||330,594 ||296,298 ||268,773 || 240,104 
|-
|[[Windsor, Ontario|Windsor]] ||329,144|| 319,246 ||323,342 ||307,877 ||278,685 || 262,075
|-
|[[Barrie, Ontario|Barrie]] ||197,059|| 187,013 ||177,061 ||148,480 || 118,695 || 97,150
|-
|[[Greater Sudbury]] ||164,689|| 160,770 ||158,258 ||155,601|| 160,488 || 157,613
|-
|[[Kingston, Ontario|Kingston]] ||161,175|| 159,561 || 152,358 || 146,838 || 143,416 || 136,401 
|-
|[[Guelph, Ontario|Guelph]] ||151,984|| 141,097 || 127,009 || 117,344 || 105,420 || 97,667
|-
|[[Brantford, Ontario|Brantford]] ||134,203|| 135,501 || 124,607 ||  86,417 || 100,238 || 97,106
|-
|[[Peterborough, Ontario|Peterborough]]||121,721|| 118,975 ||116,570 | |102,423 || 100,193 || 98,060 || -
|-
|[[Thunder Bay]] ||121,621|| 121,596 ||122,907 || 121,986 || 125,562 || 124,925
|-
|[[Belleville, Ontario|Belleville]] ||103,472 || 101,668 || 91,518 || 87,395 || 87,871 || -
|}

{| class="wikitable"
|+ 10 largest municipalities by population
|- bgcolor="#CCCCCC"
!City
!2011<ref>[https://archive.today/20120919174541/http://www12.statcan.ca/census-recensement/2011/dp-pd/hlt-fst/pd-pl/Table-Tableau.cfm?LANG=Eng&T=302&SR=1&S=12&O=A&RPP=25&PR=35 Population and dwelling counts, for Canada, provinces and territories, and census subdivisions (municipalities), 2011 and 2006 censuses - Ontario]</ref>
!2006
!2001
|-
|[[Toronto]] (provincial capital)
|2,615,060
|2,503,281
|2,481,494
|-
|[[Ottawa]] (national capital)
|883,391
|812,129
|808,391
|-
|[[Mississauga]]
|713,443
|668,549
|612,925
|-
|[[Brampton]]
|523,911
|433,806
|325,428
|-
|[[Hamilton, Ontario|Hamilton]]
|519,949
|504,559
|499,268
|-
|[[London, Ontario|London]]
|366,151
|352,395
|336,539
|-
|[[Markham, Ontario|Markham]]
|301,709
|261,573
|208,615
|-
|[[Vaughan]]
|288,301
|238,866
|182,022
|-
|[[Kitchener, Ontario|Kitchener]]
|219,153
|204,668
|190,399
|-
|[[Windsor, Ontario|Windsor]]
|210,891
|216,473
|208,402
|}

==Physical geography==
[[File:Ontario Relief.png|right|300px|thumb|Relief of Ontario]]

Southwestern Ontario and a narrow strip along the coast of the [[Saint Lawrence River]] are in the [[Mixedwood Plains]], a fertile and productive [[Ecozones of Canada|ecozone]] that is typically flat with rolling hills, and was once covered by forest before its use for [[agriculture]], and later [[urbanization]], resulted in [[deforestation]] of vast swaths of the area. To its north is the [[Boreal Shield]], the largest provincial ecozone, extending from south-central Ontario to cover most of northern Ontario, where it abuts the [[Hudson Plains]]. The [[Northwestern Ontario]] portion of this area is part of the [[Midwestern Canadian Shield forests]] ecoregion of [[boreal forest]] that spreads west through [[Manitoba]] and [[Saskatchewan]]. The plains that cover the heartland of Ontario are a transitional ecozone characterized by boreal features in the south and [[tundra]] landscapes in the north. This extends the entire range of the northern coast of Ontario with [[Hudson Bay]] and [[James Bay]], at which numerous [[wetland]]s act as [[Staging area (birds)|staging]] and nesting grounds for [[Bird migration|migratory birds]]. The waters of the two bays are in the [[Arctic Archipelago Marine]] ecozone, forming its southern, subarctic extent.

===Geology===
{{main|Geology of Ontario}}
Ontario, owing to its size, has diverse geology that varies in structure, age, and lithology. About 61% of the province is covered by the [[Canadian Shield]], mostly with [[Precambrian]] rock.<ref name="Baldwin">{{cite web |last1= Baldwin |first1= David |last2= Desloges |first2= Joseph |last3= Band |first3= Lawrence |url= http://www.ubcpress.ca/books/pdf/chapters/ecology/chapter2.pdf |title= Physical Geography of Ontario |access-date= 9 February 2013 |archive-url= https://web.archive.org/web/20071217184751/http://www.ubcpress.ca/books/pdf/chapters/ecology/chapter2.pdf |archive-date= 2007-12-17 |url-status= dead }}</ref> These rocks contain large mineral deposits that are vital to the economy of northern Ontario. The shield can further be divided into three sections. The northwestern parts of the Shield, located roughly north and west of Sudbury, are known as the Superior Province;<ref name="Baldwin" />  this is the largest of the three sections, covering about 70% of the Shield portion in Ontario.<ref name="OGS">{{cite web|last1 = Percival |first1= J. |last2= Easton |first2= R. 
|url= http://www.geologyontario.mndmf.gov.on.ca/mndmfiles/pub/data/imaging/OFR6196/OFR6196.pdf |title= Geology of the Canadian Shield in Ontario: An Update |work = Ontario Geological Survey |publisher= Geological Survey of Canada |access-date= 9 February 2013}}</ref> This region is more than 2.5 billion years old and is composed of [[felsic]] intrusive rocks.<ref name="Baldwin" /> In the northernmost parts of the Superior Province, the geology of the region is dominated by granite and gneiss rocks.<ref name="OGS" /> The central region of the Shield, known as the Grenville Province and located south of Sudbury, is 1.0 to 1.6 billion years old and is dominated by sedimentary rocks showing evidence of being subjected to metamorphism.<ref name="Baldwin" /> It makes up about 20% of the Canadian Shield in Ontario. These rocks were metamorphosed between 990 million years ago and 1.08 billion years ago. The third region, known as the Southern province which is a narrow region from Sault Ste. Marie to Kirkland Lake, is made of rocks dating 1.8 to 2.4 billion years ago.<ref name="Baldwin" />  The Hudson Bay lowlands, located north of the Canadian Shield, are mainly made of sedimentary rocks from the [[Silurian Period]], although some parts date from the [[Ordovician]] and [[Devonian]] periods.<ref name="Baldwin" /> This area covers 25% of the province. Most of the bedrock in the Hudson Bay lowlands is composed of limestone and carbonate-dominated sedimentary rock.<ref name="MNR">{{cite web |url= http://www.mnr.gov.on.ca/en/Business/Biodiversity/2ColumnSubPage/STEL02_166949.html |title= Hudson Bay Lowlands |publisher= Ontario Ministry of Natural Resources |access-date= 9 February 2013 |archive-date= 11 April 2014 |archive-url= https://web.archive.org/web/20140411115349/http://www.mnr.gov.on.ca/en/Business/Biodiversity/2ColumnSubPage/STEL02_166949.html |url-status= dead }}</ref>

===Boundaries===

The longest border is with the Canadian province of [[Manitoba]] to the west for approximately {{convert|1,025|km|mi|abbr=on}} along a line defined as the [[Northwestern point of the Lake of the Woods|Northwesternmost point]] of the [[Lake of the Woods]] to latitude 52°50' N then a diagonal line to the point where the shore of [[Hudson Bay]] meets the 89th meridian west of Greenwich.<ref>{{Cite web|url=http://digitalcommons.osgoode.yorku.ca/cgi/viewcontent.cgi?article=2152&context=rso|title=Ontario Boundary Extension Act}}</ref><ref>{{Cite web|url=http://www.amls.ca/Manitoba.htm|archive-url=https://web.archive.org/web/20070722122047/http://www.amls.ca/Manitoba.htm|url-status=dead|archive-date=2007-07-22|title=MANITOBA|date=2007-07-22|access-date=2018-04-09}}</ref>  The boundary of Ontario on Hudson and [[James Bay]] does not extend beyond the shoreline, as all islands within the bays belong to [[Nunavut]]. The border with [[Quebec]] is defined by a line due north of the head of [[Lake Timiskaming]] to James Bay,<ref>{{Cite book|url=https://en.wikisource.org/wiki/Quebec_Boundary_Extension_Act,_1898|title=Quebec Boundary Extension Act}}</ref> and southeast from there, the [[Ottawa River]] for about {{convert|620|km|mi|abbr=on}}. The boundary follows a small portion of land south of the Ottawa River until it meets the [[Saint Lawrence River]] near [[Cornwall, Ontario|Cornwall]].

Ontario also shares borders with several [[U.S. state]]s. From west to east, the [[Minnesota]] border consists of the [[Lake of the Woods]], [[Rainy River (Minnesota–Ontario)|Rainy River]], [[Rainy Lake]] and its tributaries. The border then includes the only 1&nbsp;km of land of its entire 2,700&nbsp;km U.S. border, the [[Height of Land Portage]], which divides the [[Arctic Ocean]] and [[Nelson River]] watershed from that of the [[Saint Lawrence River|St Lawrence River]] and the [[Atlantic Ocean]]. The U.S./Minnesota border then follows tributaries of the [[Pigeon River (Minnesota–Ontario)|Pigeon River]] to its mouth at Lake Superior. Ontario borders [[Michigan]] across [[Lake Superior]], the [[St. Marys River (Michigan–Ontario)|Saint Mary's River]], [[Lake Huron]], the [[St. Clair River]], [[Lake St. Clair]], the [[Detroit River]], and [[Lake Erie]]. The province also borders [[Ohio]] and [[Pennsylvania]] across Lake Erie. The 309&nbsp;km boundary with [[New York (state)|New York]] includes [[Lake Ontario]], the [[Saint Lawrence River|St. Lawrence]] and [[Niagara River|Niagara]] rivers.

===Elevation===

An extensive amount of land along the south and west shores of [[James Bay]] and [[Hudson Bay]] is low and covered with wetlands. The land in the North-east and North-west, generally north of [[Lake Superior]], is the [[Canadian Shield]] where most of Ontario's highest points are found.{{fact|date=December 2024}}

Further south, many hilltops of the Algonquin, Haliburton and Madawaska Highlands, which are also part of the shield that covers much of the north, surpass altitudes of 500&nbsp;m (1640').{{fact|date=December 2024}}

The Municipality of Temagami is located on the northeast arm of Lake Temagami, 100&nbsp;km north of North Bay. Ontario's highest point, Ishpatina Ridge (693 metres), is within the municipality's boundaries. The next highest points are in [[Dufferin County|Dufferin]], [[Grey County|Grey]] and the western side of [[Simcoe County|Simcoe]] counties, where the elevation ranges from 430&nbsp;m (1,400') to 540&nbsp;m (1,750'). Much of the higher land sits atop the [[Niagara Escarpment]] in a generally flat area known as the Dundalk Highlands. Just to the south, in [[Wellington County, Ontario|Wellington County]] and [[Waterloo Region, Ontario|Waterloo Region]], general elevations are from 300&nbsp;m (1,000') to 400&nbsp;m (1,300'). A striking topographical feature of the Niagara Escarpment is its limestone cliff face, in general between 80&nbsp;m (250') and 100&nbsp;m (330') above the surrounding land, extending from the Niagara peninsula northwest to the [[Bruce Peninsula]].<ref name="bookreference">Book: A conspectus of the Province of Ontario</ref>

The flattest areas of the province can be found in the lowlands of the far north, and in southwestern and eastern Ontario.{{fact|date=December 2024}}

===Water===
[[File:Niagara Falls and Maid of the Mist 2005.JPG|280px|right|thumb|[[Niagara Falls]], one of Ontario's most noted tourist destination and a source for hydroelectricity]]
Ontario is known for the large number of lakes and rivers it contains. About one-fifth of the world's fresh water can be found in Ontario.<ref name="freshwateralot">[https://www.ontario.ca/en/about_ontario/ONT04_020887 Water Geography information.]</ref> Ontario is also known for being the only province in Canada that touches the [[Great Lakes]]. Ontario touches four of the Great Lakes: [[Lake Huron|Huron]], [[Lake Ontario]] (the province is named after the lake), [[Lake Erie|Erie]] and [[Lake Superior|Superior]].

Ontario's vast rivers and lakes originally opened the province for exploration and have made possible hydroelectric power, mills and various forms of industrialization. Most of Ontario is fed by rainfall, and in most parts [[snow]] is relied on. Precipitation is most common in the southern and central parts of Ontario where variations among the seasons are not especially great; but winter and spring are less aqueous than in northern and northwestern Ontario.<ref>[http://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCE&Params=A1SEC875403]{{dead link|date=June 2023|bot=medic}}{{cbignore|bot=medic}} The Canadian Encyclopedia, Geography information of Ontario.</ref>

==Climate==
{{See also|Snowbelt}}
[[File:Ontario Köppen.svg|thumb|351x351px|Köppen climate types of Ontario]]
The climate of Ontario varies by season and location.<ref name=EC>{{cite web |url = http://www.on.ec.gc.ca/canada-country-study/intro.html |archive-url = https://web.archive.org/web/20130323131703/http://www.on.ec.gc.ca/canada-country-study/intro.html |archive-date = 23 March 2013 |title = The Canada Country Study: Climate Impacts and Adaptation: Ontario Region Executive Summary |publisher = Environment Canada |access-date = 29 January 2013}}</ref> It is affected by three air sources: cold, dry, arctic air from the north (dominant factor during the winter months, and for a longer part of the year in far northern Ontario); Pacific polar air crossing in from the western Canadian Prairies/US [[Northern Plains]]; and warm, moist air from the Gulf of Mexico and the Atlantic Ocean.<ref name=UBCgeo>{{cite web |first1 = David |last1 = Baldwin |first2 = Joseph |last2 = Desloges |first3 = Lawrence |last3 = Band |url = http://www.ubcpress.ca/books/pdf/chapters/ecology/chapter2.pdf |title = Physical Geography of Ontario |publisher = UBC Press |access-date = 25 March 2013 |url-status = dead |archive-url = https://web.archive.org/web/20071217184751/http://www.ubcpress.ca/books/pdf/chapters/ecology/chapter2.pdf |archive-date = 17 December 2007 }}</ref> The effects of these major air masses on temperature and precipitation depend mainly on latitude, proximity to major bodies of water and to a small extent, terrain relief.<ref name= UBCgeo/> The surrounding Great Lakes greatly influence the climatic region of southern Ontario.<ref name="EC"/> During the fall and winter months, heat stored from the lakes is released, moderating the climate near the shores of the lakes.<ref name=EPA>{{cite web |url = http://www.epa.gov/glnpo/atlas/glat-ch2.html |title = Natural Processes in the Great Lakes |publisher = US Environmental Protection Agency |access-date = 25 March 2013 |url-status = live |archive-url = https://web.archive.org/web/20130202002550/http://www.epa.gov/glnpo/atlas/glat-ch2.html |archive-date = 2 February 2013 }}</ref> This gives some parts of southern Ontario milder winters than mid-continental areas at lower latitudes.<ref name= EPA/> In general, most of Ontario's climate is classified as [[humid continental]].<ref name= UBCgeo/> 

Ontario has three main climatic regions:

===Southern Ontario===

Almost all of southern Ontario either falls in the [[Köppen climate classification]] [[Humid continental climate|'''Dfb''']] or  [[Humid continental climate|'''Dfa''']], found in [[Windsor, Ontario|Windsor]] and over a large part of [[Southwestern Ontario]], and further to the east, in the city of [[Toronto]] and over most of the southern half of the [[Golden Horseshoe]] wrapping around the west end of Lake Ontario, which encompasses the Niagara Region. Some cities straddle the zone boundary, such as [[London, Ontario|London]], the upper part of [[Hamilton, Ontario|Hamilton]], and [[Cornwall, Ontario|Cornwall]] in Southeastern Ontario. Other cities fit into the '''Dfb''' schema, including [[Kitchener, Ontario|Kitchener]], [[Barrie, Ontario|Barrie]], [[Kingston, Ontario|Kingston]] and [[Ottawa, Ontario|Ottawa]]. The region has warm, humid summers and cold, usually moist winters. Extreme heat and cold usually occur for short periods. It is considered a temperate climate when compared with the remainder of continental Canada. In the fall and winter, temperatures are moderated by the delayed cooling of the Great Lakes; this effect is reversed in spring and summer when afternoon warming is tempered. The lakes' moderating effects allow for a longer growing season than areas at similar latitudes in the continent's interior; some areas exceed 200 frost-free days and have an annual mean temperature of 10&nbsp;°C (50&nbsp;°F). Both spring and fall generally consist of mild days and cool nights but are prone to drastic temperature changes over a short timespan. Annual precipitation ranges from 75 to 110&nbsp;cm (30–43&nbsp;in) and is well distributed throughout the year with a usual summer peak. Upland areas in this region have cooler conditions, examples would be  [[Mount Forest, Ontario|Mount Forest]] and [[Bancroft, Ontario|Bancroft]], generally more precipitation (especially snowfall), putting them firmly into the '''Dfb''' climate scheme. Most of Southern Ontario lies in the lee of the Great Lakes, producing abundant snow in some areas: (London, [[Goderich, Ontario|Goderich]] and Barrie, for example) receive an average of over 2 m (80") annually, while some other areas are not in the direct line of snowbelt activity can receive on average less 1 m (40") of snow per year, such as in [[Chatham, Ontario|Chatham]] and [[Brantford, Ontario|Brantford]]. 

===Northern Ontario===
Also included in the '''Dfb''' climate are the southern reaches of including the cities of Sudbury and North Bay, which have a more severe humid continental climate. This region has warm and humid summers but with more variability, a much shorter growing season with cold, longer winters with roughly equal annual precipitation to the south. Along the eastern shores of Lake Superior and Lake Huron (including [[Georgian Bay]]), the longer winters and frequent heavy lake-effect snow squalls increase seasonal snowfall totals upwards of 3 m (120&nbsp;in) in some locations, such as [[Wawa, Ontario|Wawa]] but further north in  [[Timmins, Ontario|Timmins]] far removed from the lakes influence. 

[[Köppen climate classification]] '''Dfc''': The northernmost parts of Ontario — primarily north of 50°N and with no major cities in the area — have a [[subarctic climate]] with long, severely cold winters and short summers, with dramatic temperature changes possible in all seasons. In summer, hot weather occasionally reaches even the northernmost parts of Ontario for brief periods, although humidity is generally lower than in the south. With no major mountain ranges blocking sinking Arctic air masses, temperatures of {{convert|-40|°C|°F|abbr=on}} are not uncommon. The snow stays on the ground much longer here than in other regions of Ontario; snow cover is usually present to some extent between October and May. Surprisingly warm to hot temperatures sometimes occur in Northern Ontario communities when there is a long flow of wind from the south, as happened on 10 May 2022 when [[Moosonee]] recorded Canada's first {{convert|30|°C|°F|disp=or}} reading of the year.<ref>{{cite web | url=https://www.theweathernetwork.com/ca/news/article/you-may-never-guess-which-canadian-city-hit-30c-first-this-year | title=You may never guess which Canadian city hit 30&nbsp;°C first this year | date=11 May 2022 }}</ref>

===Severe weather===

Severe and non-severe thunderstorms peak in frequency from June through August but can occur at any time. Thunderstorm activity is frequent, and occasionally severe across the South, but also in Central and [[Northwestern Ontario]]. Thunderstorms form from daytime convective heating and frontal activity; in the south, lake breeze convergences also intensify storms. Another severe type of thunderstorm is known as a [[Mesocyclonic Convective Complex]] or [[Derecho]], which is a larger cluster-type thunderstorm mass with a more or less circular shape, often with a pronounced bow shape at its front or leading edge. During periods of hot weather in summer, they often develop in the afternoon west of the Great Lakes then strike Southern and Central Ontario at night with great forward motion, bringing severe straight-line winds over wide areas resulting in damage to forests, power interruption and infrastructure damage. The areas with the highest severe weather frequency in the province are Southwestern (Windsor, Chatham, Stratford corridor) and Central Ontario (Simcoe County including the city of Barrie, [[Lake Simcoe]] and the [[Kawartha Lakes]] region), both areas often getting amplified storms resulting from the Lake Breeze Front convergence. London has the most lightning strikes per year in Canada, averaging 34 days of thunderstorm activity per year. In a typical year, based on averages from the period from 1980 to 2009 compiled by the Northern Tornadoes Project,<ref>{{cite web|title=Northern Tornadoes Project|access-date=28 August 2024|url=https://www.uwo.ca/ntp/index.html}}</ref> Ontario averaged 18.2 confirmed [[tornado]] touchdowns per year.<ref>{{cite web|title=Ontario is now Canada's tornado hot spot — and the season is getting longer|access-date=28 August 2024|url=https://globalnews.ca/news/10562660/ontario-tornadoes-canada/}}</ref> 
There were a record 29 tornadoes conformed in both 2006 and 2009.
These tornadoes, however, are only on occasion destructive (the vast majority are classified as EF0 or EF1 on the Enhanced Fujita scale). In Northern Ontario, some tornadoes go undetected by ground spotters because of the sparse population and remote landscape; they are often discovered after the fact by aircraft pilots, where aerial observations of damaged forest confirm occurrences. All of Northern Ontario north of a line from [[Lake Nipigon]] to [[Timmins]] has no weather radar coverage by [[Environment Canada]] making it difficult to detect tornadoes in far northern Ontario when they occur. Tropical depression remnants can cause copious rains and winds in the south, but are rarely deadly. A notable exception was [[Hurricane Hazel]] in October 1954.

===Climate charts===

{{climate chart
| Windsor
|-7.1|-0.0|70.8
|-6.4| 1.3|60.0
|-2.1| 6.8|71.0
| 3.5|14.0|92.2
| 9.8|20.7|97.3
|15.5|26.0|82.9
|18.0|28.3|99.3
|17.1|27.0|75.7
|13.0|23.1|88.3
| 6.9|16.1|73.9
| 1.4| 8.9|73.2 
|-3.5| 2.7|69.2
|float  = left
|clear  = none
|source = <ref>https://climate.weather.gc.ca/climate_normals/results_1991_2020_e.html?searchType=stnName_1991&txtStationName_1991=windsor&searchMethod=contains&txtCentralLatMin=0&txtCentralLatSec=0&txtCentralLongMin=0&txtCentralLongSec=0&stnID=217000000&dispBack=0</ref>
}}

{{climate chart
| Toronto
| -6.7 | -0.3 | 65
| -6.0 |  0.6 | 54
| -1.8 |  5.1 | 53
|  3.9 | 11.7 | 76
| 10.0 | 18.8 | 82
| 15.3 | 24.2 | 77
| 18.1 | 27.0 | 72 
| 17.7 | 26.1 | 81 
| 13.8 | 22.0 | 85
|  7.7 | 14.6 | 64
|  2.3 |  8.1 | 71 
| -2.7 |  2.6 | 58 
|float  = left
|clear  = none
|source = <ref>[https://climate.weather.gc.ca/climate_normals/results_1991_2020_e.html?searchType=stnName_1991&txtStationName_1991=toronto&searchMethod=contains&txtCentralLatMin=0&txtCentralLatSec=0&txtCentralLongMin=0&txtCentralLongSec=0&stnID=207000000&dispBack=0|Toronto) Canadian Climate Normals 1991-2020 (Toronto City)]</ref>
}}

{{climate chart
| Ottawa
|-14.0 |-5.2 |65.2 
|-12.9 |-3.3 |52.4
|-6.9 |2.5 |61.6
|1.1 |11.2 |81.3 
|8 |19.4 |80.1
|13.3 |24.2 |95.1
|15.8 |26.7 |92.3
|14.6 |25.6 |87.4 
|10.1 |21.1 |87.0
|4.1 |13.3 |90.2 
|-1.8 |5.8 |72.0
|-8.7 |-1.5 |73.6 
|float  = left
|clear  = none
|source = <ref>[https://climate.weather.gc.ca/climate_normals/results_1991_2020_e.html?searchType=stnName_1991&txtStationName_1991=ottawa&searchMethod=contains&txtCentralLatMin=0&txtCentralLatSec=0&txtCentralLongMin=0&txtCentralLongSec=0&stnID=450000000&dispBack=0 Canadian Climate Normals 1991-2020 (Ottawa City)]</ref>
}}

{{climate chart
| Sudbury
|-17.5 |-7.8 |66.8
|-16.3 |-5.9 |51.1
|-10.2 |0.5 |58.3
|-2.0 |8.6 |67.8 
|5.3 |17.4 |79.2
|11.0 |22.6 |77.4 
|13.4 |25.0 |84.0
|12.5 |23.5 |89.9 
|8.1 |18.6 |103.2
|1.9 |10.6 |93.8
|-4.4 |2.9 |74.5
|-11.7 |-3.9 |65.9
|float  = left
|clear  = none
|source = <ref>[https://climate.weather.gc.ca/climate_normals/results_1991_2020_e.html?searchType=stnName_1991&txtStationName_1991=sudbury&searchMethod=contains&txtCentralLatMin=0&txtCentralLatSec=0&txtCentralLongMin=0&txtCentralLongSec=0&stnID=203000000&dispBack=1 Canadian Climate Normals 1991-2020 (Sudbury)]</ref>
}}

{{climate chart
| Thunder Bay
|-19.2 |-7.6 |31.3
|-18.3 |-5.2 |24.9
|-11.8 |1.0 |41.6
|-1.9 |8.9 |41.5
|1.9 |15.9 |66.5
|7.8 |21.6 |85.7
|11.0 |24.9 |89
|10 |24.2 |87.5
|5.5 |19.2 |88
|-0.3 |10.9 |62.6
|-6.7 |2.6 |55.6
|-14.6 |-4.5 |37.5
|float  = left
|clear  = none
|source = <ref>[https://climate.weather.gc.ca/climate_normals/results_1991_2020_e.html?searchType=stnName_1991&txtStationName_1991=thunder+bay&searchMethod=contains&txtCentralLatMin=0&txtCentralLatSec=0&txtCentralLongMin=0&txtCentralLongSec=0&stnID=204000000&dispBack=1 Canadian Climate Normals 1991-2020 (Thunder Bay)]</ref>
}}

{{climate chart
| Moosonee
|-24.4 |-13.0 |33.9
|-23.9 |-10.8 |22.7
|-18.0 |-4.0 |31.7
|-8.1 |3.8 |39
|-0.3 |12.7 |53.7
|5.7 |19.8 |71.1
|9.8 |22.9 |101.3
|9.4 |21.6 |75.8
|5.8 |16.9 |90
|0.6 |8.9 |73.3
|-7.5 |0.1 |54.3
|-18.2 |-8.8 |34.7
|float  = left
|clear  = none
|source = <ref>[https://climate.weather.gc.ca/climate_normals/results_1991_2020_e.html?searchType=stnName_1991&txtStationName_1991=moosonee&searchMethod=contains&txtCentralLatMin=0&txtCentralLatSec=0&txtCentralLongMin=0&txtCentralLongSec=0&stnID=185000000&dispBack=1Canadian Climate Normals 1991-2020 (Moosonee)]</ref>
}}

{{climate chart
| Big Trout Lake
|-27.1 |-16.6 |23
|-26.4 |-13.4 |20.6
|-19.7 |-5.1 |27.9
|-9.8 |3.8 |32.2
|-0.9 |12 |37.8
|6.5 |18.4 |74.3
|10.2 |22.4 |90.9
|9.5 |20.6 |87.8
|4.9 |14.3 |83
|-1.3 |5.5 |52.7
|-11.7 |-4.6 |50.1
|-22.3 |-13.5 |28.8
|float  = left
|clear  = none
|source = <ref>[https://climate.weather.gc.ca/climate_normals/results_1991_2020_e.html?searchType=stnName_1991&txtStationName_1991=big+trout+lake&searchMethod=contains&txtCentralLatMin=0&txtCentralLatSec=0&txtCentralLongMin=0&txtCentralLongSec=0&stnID=154000000&dispBack=1 Canadian Climate Normals 1991-2020 (Big Trout Lake)]</ref>
<ref>[http://climate.weatheroffice.gc.ca/climate_normals/results_e.html?stnID=3914&lang=e&dCode=0&province=ONT&provBut=&month1=0&month2=12 Canadian Climate Normals 1971-2000 (Big Trout Lake)]</ref>
}}
{{Clear}}

==See also==
{{Portal|Geography|Canada}}
*[[Geology of Ontario]]
*[[Geography of Canada]]
*[[Demographics of Ontario]]
*[[List of islands of Ontario]]
*[[Southern Ontario]]
*[[Ontario Peninsula]]
*[[Northern Ontario]]

==References==
{{Reflist|30em}}

==External links==
*[https://www.ontario.ca/en/about_ontario/EC001032.html?openNav=geography Geography of Ontario at www.ontario.ca] {{Webarchive|url=https://web.archive.org/web/20121031030038/https://www.ontario.ca/en/about_ontario/EC001032.html?openNav=geography |date=31 October 2012 }}

{{Ontario}}
{{Subdivisions of Ontario}}
{{Canada Geography}}

[[Category:Geography of Ontario| ]]