The climate of Thunder Bay is influenced by Lake Superior, resulting in cooler summer temperatures and warmer winter temperatures. So when visiting, it’s important to pack for cooler weather and plan to wear layers that can easily accodate the temperature for that part of the day.

The average daily temperatures range from a high of 62 F/17.6 °C in July and a low of 5°F/-14.8 °C in January; the average daily high in July is 75°F/24.2 °C and the average daily high in January is 17°F/-8.6 °C. Summer daytime temperatures vary from 15° C to 30° C, while nights tend to be cooler and less humid than southern locations.

The summer period is well suited to both active and passive outdoor recreational pursuits. Recent winter daytime temperatures have ranged from springlike to relatively cold with sunny days. This type of climate is well suited to all kinds of active outdoor recreational pursuits. Spring and autumn are short with cool days and evenings.

Winter outdoor recreation often extends well into April while summer culminates in a spectacular show of colours in the fall.Precipitation is highly variable from year to year. The annual average rainfall is 527.3 mm while the average snowfall is 213 cm.
On average, Thunder Bay is the sunniest location in eastern, sunnier than any city in Canada located to the east of it.

Current Thunder Bay Weather

Observed at Thunder Bay Airport on 2010-09-02 23:00:00

	15°C Light Rain
		Feels Like		Wind	SE 5 km/h
		Humidity	100 %	Pressure	100.2 kPa falling
		Dew Point	15.0°C	Visibility	9.7 km
		Air Quality		Temperature	15.0°C

Short Term Forecast

	Thursday Night	Friday	Friday Night	Saturday	Sunday
	Rain At Times Heavy	Periods Of Rain	Periods Of Rain	A Mix Of Sun And Cloud	Sunny
Low	12°C		6&°C		4&°C
High		12°C		16°C	18°C

Detailed Thunder Bay Weather Forecast

Thursday Night	A few showers changing to rain at times heavy this evening. Risk of a thunderstorm this evening and after midnight. Amount 30 to 40 mm. Wind east 20 km/h becoming light this evening. Low 12. Forecast issued 4:00 PM EDT Thursday 02 September 2010
Friday	Periods of rain. Amount 10 mm. Wind becoming northwest 40 km/h gusting to 70 in the morning. High 12. Forecast issued 4:00 PM EDT Thursday 02 September 2010
Friday Night	Periods of rain ending in the evening then cloudy periods. Wind northwest 30 km/h gusting to 50. Low 6. Forecast issued 4:00 PM EDT Thursday 02 September 2010
Saturday	A mix of sun and cloud. High 16. Forecast issued 4:00 PM EDT Thursday 02 September 2010
Sunday	Sunny. Low plus 4. High 18. Forecast issued 4:00 PM EDT Thursday 02 September 2010
Monday	A mix of sun and cloud. Low plus 3. High 17. Forecast issued 4:00 PM EDT Thursday 02 September 2010
Tuesday	Cloudy with 60 percent chance of showers. Low 12. High 20. Forecast issued 4:00 PM EDT Thursday 02 September 2010
Wednesday	Cloudy. Low 13. High 22. Forecast issued 4:00 PM EDT Thursday 02 September 2010