The isolated northernmost part of Ontario has a subarctic climate, while the province’s much more populous south experiences a humid continental climate similar to the northeastern United States. The Great Lakes and Georgian Bay which surround southern Ontario delay its fall frosts, decrease its winter temperatures, and add humidity to its warm summers.
Most of Ontario receives plenty of rain and snow thanks to frequent meetings between moist and warm southern air and cold northern polar air. Southern Ontario experiences more rainfall than northern Ontario, but the province’s heaviest snowfalls occur around Georgian Bay and Lake Huron. One city, Owen Sound, has experienced over 135 inches of snow in a single year.
January is the coldest month in all of Ontario, but average daytime temperatures vary dramatically from a frigid 9°F in the Ottawa River valley to a comparatively mild 25°F in southwestern Ontario. Average July temperatures range between 64°F in eastern Ontario to 74°F in southwestern Ontario.
Best Time to Visit Ontario
Summer is Ontario’s hottest and busiest tourism season, when most tourist attractions are open and most outdoor festivals take place. Summer visitors must wear protective hats and plenty of sunscreen to prevent sunburn during southern Ontario’s often high temperatures. Umbrellas and rain gear are recommended at all times of the year, but especially during spring, Ontario’s rainiest season.
Early fall brings even more rain to some parts of Ontario, and snow may even fall in northern Ontario as early as October. Ontario’s fall season, however, is generally pleasantly crisp and filled with colorful foliage. Fall is monarch butterfly migration season in Point Pelee National Park. Visitors willing to brave Ottawa’s cold winter temperatures can enjoy the city’s Winterlude celebrations and ice skate along the Rideau Canal.