Weather and Climate

Ontario’s climate is considered continental, with temperatures ranging from humid in the south, with cold winters and warm summers, to sub-Arctic in the north. Due to Ontario’s size, temperatures may vary from region to region and even within the regions themselves. The large bodies of water in the north and south have a moderating effect on the climate, with less extreme temperatures during the summer and winter months. This effect also reduces the differences between day and night temperatures.

Given Sarnia-Lambton’s location in Southwestern Ontario, it has a moderate humid continental climate. The region has hot, humid summers and cold winters. It is considered a temperate climate when compared with most of Canada. In the summer, the air masses often come out of the southern United States, and warm, humid air is drawn northward from the Gulf of Mexico. Throughout the year, but especially in the fall and winter, temperatures are moderated somewhat by the lower Great Lakes, making it considerably milder than the rest of the provinces and allowing for a longer growing season than areas at similar latitudes in the continent’s interior. Both spring and fall are generally pleasantly mild, with cool nights.

On average, the coldest month of the year is January and the warmest is July. The January average is about -5°C (23°F). The average temperatures in July are 22°C (72°F).

The cold polar air from the north meeting the warm, moist air from the south causes precipitation throughout the year. During the winter months, most of Ontario is blanketed with snow, especially in the north. In Sarnia-Lambton, precipitation averages about 80 cm (32 in.) per year with slightly lower levels of snowfall than the rest of the province. However, just to the north, annual snowfalls east of Lake Huron and Georgian Bay, can exceed 339 cm (134 in.).

Temperatures are given officially in degrees Celsius (°C) with the Fahrenheit equivalent (°F) often added. For an exact conversion of Celsius to Fahrenheit, multiply the Celsius temperature by 9, divide that answer by 5, then add 32. Environment Canada provides a current Ontario weather update and local forecasts.

Located in Southwestern Ontario, Sarnia-Lambton’s climate is one of the warmest in Canada yet still offers the appeal of four seasons.


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