Weather in Thunder Bay: August
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Average day temperature: | 69.1°F |
| Average night temperature: | 58.9°F | |
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Sea water temperature: | 63.3°F |
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Number of sunny days: | 14 days |
| Day length: | 13.4 - 15.0 hours | |
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Number of rainy days: | 2 days |
| Precipitation totals: | 1.0 in. | |
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forecast
| Thunder Bay |
temperature
| Thunder Bay |
Air temperature in August, °F
The highest day temperature during August of 2025 was 79°F. At the same time the lowest night temperature was 46°F. Daily and nightly averages during August were 69.7°F and 57.7°F.
Sea water temperature in Thunder Bay in August, °F
The average sea water temperature in August of 2025 was 63.2°F. The highest and lowest sea temperatures during the month were 68.0°F and 59.9°F.
Mostly all days in August are sunny but cloudy days are also possible.
Precipitation total in August, in.
Precipitation total value in Thunder Bay in August is 1.0 in. Other months of the year show relatively similar values.
The average wind speed value in August is 6.6 mph It makes August one of the least windy months of the year.
This chart shows average number of hours during the day when sunlight can reach the ground. It depends on day length and cloudiness during the day. The average number of sunny hours in August is: 8.6.
Best time for vacation in Thunder Bay
Thunder Bay on a weather map
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