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Weather in Thunder Bay for September 2025

Your guide to Thunder Bay weather in September - trends and predictions

    Temperatures

  • In general, the average temperature in Thunder Bay at the beginning of September is 22.7 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 19.3 °C by the end of September.

  • Rain 🌧️

  • Thunder Bay experiences moderate rainfall in September, with an average of 9 rainy days and a total precipitation of 58.2 mm.

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Average dry days
21
Dry days
Average rainy days
9
Rainy days
Average snowy days
0
Snow days
Average temperatures
20°/11°
Temperatures
Average wind speed
15 km/h
Avg max wind
Average humidity
77 %
Avg humidity

Thunder Bay in September average weather

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Temperatures trend during September in Thunder Bay

See the weather trend as well as the moving average line

September weather day by day

Click on a date for more information
Date Weather Temperatures Rain UV More
1 Sept. Patchy rain possible
Patchy rain possible
22° /10° 0.1 mm 6
2 Sept. Sunny
Sunny
26° /12° 0 mm 7
3 Sept. Partly cloudy
Partly cloudy
27° /14° 0.2 mm 7
4 Sept. Partly cloudy
Partly cloudy
24° /15° 0 mm 6
5 Sept. Fog
Fog
24° /12° 6.2 mm 6
6 Sept. Light rain shower
Light rain shower
17° /7° 16.5 mm 4
7 Sept. Partly cloudy
Partly cloudy
19° /5° 0 mm 6
8 Sept. Mist
Mist
20° /5° 0 mm 5
9 Sept. Light drizzle
Light drizzle
18° /10° 5.9 mm 5
10 Sept. Light rain shower
Light rain shower
20° /11° 1.5 mm 5
11 Sept. Overcast
Overcast
19° /11° 0 mm 5
12 Sept. Overcast
Overcast
18° /9° 0 mm 5
13 Sept. Sunny
Sunny
21° /9° 0 mm 6
14 Sept. Mist
Mist
19° /8° 0 mm 5
15 Sept. Mist
Mist
22° /13° 0.9 mm 5
16 Sept. Mist
Mist
21° /13° 3.7 mm 5
17 Sept. Overcast
Overcast
19° /11° 6.2 mm 5
18 Sept. Overcast
Overcast
19° /11° 7.8 mm 5
19 Sept. Mist
Mist
19° /10° 0 mm 5
20 Sept. Patchy rain possible
Patchy rain possible
20° /14° 0.5 mm 5
21 Sept. Mist
Mist
21° /12° 0 mm 5
22 Sept. Light rain shower
Light rain shower
18° /11° 6 mm 4
23 Sept. Patchy rain possible
Patchy rain possible
17° /9° 0 mm 5
24 Sept. Overcast
Overcast
17° /9° 0 mm 4
25 Sept. Overcast
Overcast
21° /10° 0 mm 5
26 Sept. Partly cloudy
Partly cloudy
19° /11° 0 mm 5
27 Sept. Fog
Fog
19° /10° 0 mm 5
28 Sept. Mist
Mist
20° /10° 0 mm 5
29 Sept. Fog
Fog
19° /11° 0.9 mm 5
30 Sept. Light rain shower
Light rain shower
20° /9° 1.7 mm 5
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Important Notice
Our weather forecast for Thunder Bay in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Thunder Bay forecast closer to your planned date for the most up-to-date weather information.

Thunder Bay in September - FAQ

What are the expected maximum and minimum temperatures in Thunder Bay during September?
Enjoy moderate daytime temperatures of up to 20° and cooler nights around 11°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Thunder Bay during September?
Moderate rainfall is anticipated in Thunder Bay during September, with a total of 58.2 mm spread over approximately 9 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in Thunder Bay during September?
The average wind speed in Thunder Bay during September is 15 km/h, suggesting breezy to windy conditions, depending on your activities.

September rainfall patterns in Thunder Bay

Explore the daily rainfall trends and prepare for Thunder Bays September weather 💧

UV exposure in Thunder Bay during September

Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️

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Location coordinates Where is Thunder Bay?

Get accurate weather forecasts for Thunder Bay, located at latitude 48.382 and longitude -89.25. Stay updated with localized weather information tailored for Thunder Bay.

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