Thunder Bay (ON) Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Thunder Bay.
Climate overview of Thunder Bay
Thunder Bay, Ontario, Canada, experiences significant temperature variation throughout the year. Summers bring daytime highs of 23°C (73°F) in August, while winters cool to -8°C (18°F) in January.
The city receives around 744 mm (29 in) of rain/snowfall per year. It experiences a distinct dry season from January to March. September is the wettest month and February the driest.
Thunder Bay Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Thunder Bay — and find the best time to visit.
Monthly Temperature in Thunder Bay
Depending on the time of the year, temperatures range from comfortable to very cold in Thunder Bay. On average, daytime temperatures range from a comfortable 23°C (73°F) in August to a very cold -8°C (18°F) in January.
Nighttime temperatures range from 14°C (57°F) in August to -17°C (1°F) in January.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Thunder Bay
Generally, Thunder Bay has a moderate amount of precipitation, averaging 744 mm (29 in) of rain/snowfall annually. The seasons in Thunder Bay bring significant changes in precipitation. The wettest month, September, receives moderate rainfall, with an average of 93 mm (3.7 in) of precipitation. This rainfall is distributed across 13 rainy days.
In contrast, the driest month, February, experiences much less snowfall, totaling 30 mm (1.2 in) over 9 snowy days. These distinct seasonal differences provide diverse experiences throughout the year. For more details, please visit our Thunder Bay Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Best Time to Visit Thunder Bay
Rainfall during this time ranges from 72 mm (2.8 in) in August to 93 mm (3.7 in) in September. This means you can expect a mix of sunny days and occasional showers. Need help choosing your next travel destination? We offer a specialized tool that matches you with locations based on your weather preferences. Explore destinations that suit your climate preferences.
Frequently asked questions about the climate in Thunder Bay
What is the best time to visit Thunder Bay?
July and August typically offer the most optimal weather in Thunder Bay. In contrast, January, February, March, April, November and December tend to have less optimal conditions. Thunder Bay has a distinct dry season from January to March.
What temperatures can I expect in Thunder Bay?
Daytime highs range from -8°C (18°F) in January to 23°C (73°F) in August. Nighttime lows range from -17°C (1°F) to 14°C (57°F). Temperatures vary considerably through the year.
How much rain does Thunder Bay get?
Annual rainfall is around 744 mm (29 in). September is the wettest month with 93 mm (3.7 in), while February is the driest with 30 mm (1.2 in).
Thunder Bay 3-Day Forecast
Thunder Bay (ON) 3-Day Forecast
Thunder Bay on the map
Thunder Bay is highlighted — select any city to see its climate.
Popular this month
Where to go in June — average daytime high across popular destinations.
Montréal
25°C (77°F) Niagara Falls
25°C (77°F) Ottawa25°C (77°F) Quebec City
23°C (73°F) Toronto22°C (72°F) Calgary20°C (68°F) Vancouver19°C (66°F) Whistler15°C (59°F) 
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