Ontario is located in East/Central Canada. It is Canada's second largest province by land area. Its physical features vary greatly from the Mixedwood Plains in the southeast to the 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 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.The population of communities in the Golden Horseshoe.

Population

Ontario is the most populous province in Canada. Southern Ontario is one of the densest regions in the country. 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 urbanized province after British Columbia, with 85.9% of the population living in urban areas.

+ Population by Statistical Area ClassificationPopulation and dwelling counts, for Canada, provinces and territories by the Statistical Area Classification, 2011 and 2006 censusesStatistical Area Classification 2011 Census 2006 Census Change Population % of total Population % of totalWithin CMAs 10,270,006 79.9% 9,591,529 78.9% 7.1%Within CAs 1,133,127 8.8% 1,128,614 9.3% 0.4% Total CMA/CA 11,403,133 88.7% 10,720,143 88.2% 6.4%Strongly influenced 644,299 5.0% 631,410 5.2% 2.0%Moderately influenced 555,931 4.3% 554,062 4.5% 0.3%Weakly influenced 225,197 1.8% 232,107 1.9% 3.0%Not influenced 23,261 0.2% 22,560 0.2% 3.1%Outside CMA/CA 1,448,688 11.3% 1,440,139 11.8% 0.6%Total 12,851,821 100.0% 12,160,282 100.0% 5.7%

+ Census Metropolitan Areas (CMAs) by populationCity2016201120062001 19961991Toronto 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 1,010,498 941,814Hamilton 747,545 721,053 692,911 662,401 624,360 599,760Kitchener-Cambridge-Waterloo 523,894 477,160 451,235 414,284382,940 356,421 London 494,069 474,786 457,720 432,451 398,616 381,522St. Catharines-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 329,144 319,246 323,342 307,877 278,685 262,075Barrie 197,059 187,013 177,061 148,480 118,695 97,150Greater Sudbury 164,689 160,770 158,258 155,601 160,488 157,613Kingston 161,175 159,561 152,358 146,838 143,416 136,401 Guelph 151,984 141,097 127,009 117,344 105,420 97,667Brantford 134,203 135,501 124,607 86,417 100,238 97,106Peterborough121,721 118,975 |102,423 100,193 98,060 -Thunder Bay 121,621 121,596 122,907 121,986 125,562 124,925Belleville 103,472 101,668 91,518 87,395 87,871 -

+ 10 largest municipalities by populationCity201120062001Toronto (provincial capital)2,615,0602,503,2812,481,494Ottawa (national capital)883,391812,129808,391Mississauga713,443668,549612,925Brampton523,911433,806325,428Hamilton519,949504,559499,268London366,151352,395336,539Markham301,709261,573208,615Vaughan288,301238,866182,022Kitchener219,153204,668190,399Windsor210,891216,473208,402

Physical geography

Southwestern Ontario and a narrow strip along the coast of the Saint Lawrence River are in the Mixedwood Plains, a fertile and productive 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 wetlands act as staging and nesting grounds for migratory birds. The waters of the two bays are in the Arctic Archipelago Marine ecozone, forming its southern, subarctic extent.

Boundaries The longest border is with the Canadian province of Manitoba to the west for approximately along a line defined as the 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. 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, and southeast from there, the Ottawa River for about . The boundary follows a small portion of land south of the Ottawa River until it meets the Saint Lawrence River near Cornwall.

Ontario also shares borders with several U.S. states. From west to east, the Minnesota border consists of the Lake of the Woods, Rainy River, Rainy Lake and its tributaries. The border then includes the only 1 km of land of its entire 2,700 km U.S. border, the Height of Land Portage, which divides the Arctic Ocean and Nelson River watershed from that of the St Lawrence River and the Atlantic Ocean. The U.S./Minnesota border then follows tributaries of the Pigeon River to its mouth at Lake Superior. Ontario borders Michigan across Lake Superior, the 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 km boundary with New York includes Lake Ontario, the St. Lawrence and 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.

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 m (1640').

The Municipality of Temagami is located on the northeast arm of Lake Temagami, 100 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, Grey and the western side of Simcoe counties, where the elevation ranges from 430 m (1,400') to 540 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 and Waterloo Region, general elevations are from 300 m (1,000') to 400 m (1,300'). A striking topographical feature of the Niagara Escarpment is its limestone cliff face, in general between 80 m (250') and 100 m (330') above the surrounding land, extending from the Niagara peninsula northwest to the Bruce Peninsula.Book: A conspectus of the Province of Ontario

The flattest areas of the province can be found in the lowlands of the far north, and in southwestern and eastern Ontario.

Water

Ontario is known for the large number of lakes and rivers it contains. Ontario contains more than 250,000 lakes (including those forming part of the Great Lakes). The Great Lakes are a large binational system shared between Canada and the United States, which hold roughly 20% of the world’s fresh surface water; this figure reflects the volume of the Great Lakes as a whole, not the many smaller lakes across Ontario. Ontario is also known for being the only province in Canada that touches the Great Lakes. Ontario touches four of the Great Lakes: Huron, Lake Ontario (the province is named after the lake), Erie and 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. The Canadian Encyclopedia, Geography information of Ontario.

Climate

The climate of Ontario varies by season and location. 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. 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. The surrounding Great Lakes greatly influence the climatic region of southern Ontario. During the fall and winter months, heat stored from the lakes is released, moderating the climate near the shores of the lakes. This gives some parts of southern Ontario milder winters than mid-continental areas at lower latitudes. In general, most of Ontario's climate is classified as humid continental.

Ontario has three main climatic regions:

Southern Ontario

Almost all of southern Ontario either falls in the Köppen climate classification Dfb or Dfa, found in 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, the upper part of Hamilton, and Cornwall in Southeastern Ontario. Other cities fit into the Dfb schema, including Kitchener, Barrie, Kingston and 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 °C (50 °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 cm (30–43 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 and 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 and Barrie, for example) receive an average of over annually, while some other areas are not in the direct line of snowbelt activity can receive on average less of snow per year, such as in Chatham and Brantford.

Northern Ontario