Ontario Canada Weather
And Climate



Ontario Canada weather falls mostly within the Northern Climate Region of Canada.

However, about one sixth of Ontario weather occurs south of North Bay and Sudbury, within the Southeastern Climate Region.

The presence of the freshwater Great Lakes has an undeniable influence on the latter, while Hudson Bay, and James Bay, have one on the former.

Southern Ontario


Toronto International Airport, Ontario, Canada - Graph of Normals. Source of data: Environment Canada.



Lakes Erie and Ontario lie in one of the major storm tracks of the North-American Continent. The alternating storms and anti-cyclones contribute to the changing southern Ontario Canada weather patterns, especially in winter!

In the summer, this region can sometimes be under a southwesterly flow of heated air from the central United States. When such an event occurs, it is never without humidity, injected into the hot air flow by contact with the lower Great Lakes.

In a sense, it never rains, but it pours in southwestern Ontario, in the summer. There are normally 20 to 30 days with thunderstorms each summer. Otherwise, the region normally gets a lot of sunshine from June to early September, with only brief interruptions by convective clouds.

Fortunately, severe winter storms, or summer heat waves are usually of short duration … but some of them can leave a lasting impression!



Northern Ontario

Summers are warm, with mean temperatures around 15C in July, in the north, to near 20C in the southern portion, of which Sault Ste Marie, Sudbury, and North Bay are the boundary.

Sudbury Ontario Canada Normals. Source of data: Environment Canada

Summer heat waves are not uncommon in northern Ontario. Maximum temperatures can sometimes rise in the mid thirties Centigrade!

Except for sectors adjacent to the shores of Lake Superior, and Northern Lake Huron, this region normally experiences very cold winters.

Geraldton Ontario Canada Graph of Normals. Source of data: Environment Canada.

Normally 500mm to 750mm of precipitation will fall on northern Ontario, the greater portion of which will fall in the summer. However, the steep northeastern shores of Lake Superior can receive annual amounts in excess of 1100mm!

Stay tuned, and keep a sharp weather watch!


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