Northwestern Ontario has a climate with four distinct seasons; spring summer, fall and winter. This area of Ontario is known for its sub-arctic climate, with very cold winters and warm summers.

Residents take pleasure in longer days with as many as 16:00 daylight hours in the summer and 8.50 in the winter. On average, Thunder Bay is the sunniest location in Ontario with over 2200 hours of sunshine per year.

Four seasons:

Season Duration (months)
Spring March to May 
Summer June to August
Fall September to November
Winter December to February

Located in the northern hemisphere, daily temperatures in Northwestern Ontario vary depending on the season and can change dramatically.

  • Spring temperatures and conditions are varied, ranging from 0ºC and dry in early April to 20ºC and wet in mid-May.
  • Summers are generally warm and dry with the hottest temperatures in July and early August. In the peak summer months, temperatures of 30 °C or more are not uncommon. 
  • Fall is known for its beauty as the trees turn colours from green into gold, orange, red and amber. Fall weather generally brings milder temperatures and frosty mornings
  • Winters are cold with average temperatures ranging from a low of -15ºC to -30ºC in January. Winters bring a unique mix of snow, crisp sunshine, cold winds and blue skies. With constant cold temperatures of -15 °C and below, snowfall remains on the ground for several months providing excellent conditions for traditional winter activities.

Precipitation is highly variable from year to year across Northwestern Ontario. The annual average rainfall is 527.3 mm while the average snowfall is 213 cm. 

Warm to hot summers, cold winters and temperate fall and spring seasons generally allow a year-round outdoor lifestyle. The climate of the communities located along the north shore is influenced by Lake Superior, resulting in slightly cooler summer temperatures and warmer winter temperatures than the rest of the region.

For detailed information on specific locations in Northwestern Ontario visit the Environment Canada Weather Office.

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