Ottawa
September
Weather in Ottawa for September 2025
Your guide to Ottawa weather in September - trends and predictions
In general, the average temperature in Ottawa at the beginning of September is 25.3 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 20.4 °C by the end of September.
With an average of 5 rainy days, Ottawa experiences minimal rainfall in September.
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25
Dry days
5
Rainy days
0
Snow days
23°/11°
Temperatures
12 km/h
Avg max wind
72 %
Avg humidity
Ottawa in September average weather
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| Mon. | Tue. | Wed. | Thu. | Fri. | Sat. | Sun. |
|---|---|---|---|---|---|---|
| 1  24° | 2 22° | 3  25° | 4 27° | 5 28° | 6  28° | 7 23° |
| 8  16° | 9  21° | 10 21° | 11 23° | 12 24° | 13 21° | 14 21° |
| 15  24° | 16 25° | 17  25° | 18 23° | 19 24° | 20 21° | 21 21° |
| 22 22° | 23 19° | 24 22° | 25  18° | 26 20° | 27 20° | 28 20° |
| 29 21° | 30 22° |
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Temperatures trend during September in Ottawa
See the weather trend as well as the moving average line
September weather day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| 1 Sept. | Overcast | 24° /10° | 2.9 mm | 6 | |
| 2 Sept. | Overcast | 22° /10° | 0 mm | 5 | |
| 3 Sept. | Mist | 25° /10° | 0 mm | 7 | |
| 4 Sept. | Overcast | 27° /14° | 0 mm | 7 | |
| 5 Sept. | Mist | 28° /15° | 0 mm | 7 | |
| 6 Sept. | Thundery outbreaks possible | 28° /15° | 0.2 mm | 6 | |
| 7 Sept. | Thundery outbreaks possible | 23° /12° | 8.1 mm | 5 | |
| 8 Sept. | Light rain | 16° /10° | 2.2 mm | 4 | |
| 9 Sept. | Cloudy | 21° /7° | 0 mm | 5 | |
| 10 Sept. | Overcast | 21° /9° | 0 mm | 5 | |
| 11 Sept. | Overcast | 23° /9° | 0 mm | 5 | |
| 12 Sept. | Fog | 24° /13° | 0.1 mm | 6 | |
| 13 Sept. | Mist | 21° /12° | 0.1 mm | 6 | |
| 14 Sept. | Mist | 21° /10° | 0 mm | 5 | |
| 15 Sept. | Partly cloudy | 24° /10° | 0 mm | 6 | |
| 16 Sept. | Partly cloudy | 25° /12° | 0 mm | 7 | |
| 17 Sept. | Patchy rain possible | 25° /13° | 0.6 mm | 6 | |
| 18 Sept. | Patchy light drizzle | 23° /12° | 0.8 mm | 5 | |
| 19 Sept. | Thundery outbreaks possible | 24° /14° | 0 mm | 6 | |
| 20 Sept. | Overcast | 21° /11° | 0 mm | 5 | |
| 21 Sept. | Mist | 21° /9° | 0 mm | 5 | |
| 22 Sept. | Overcast | 22° /9° | 0 mm | 5 | |
| 23 Sept. | Mist | 19° /11° | 3.8 mm | 5 | |
| 24 Sept. | Mist | 22° /12° | 0 mm | 5 | |
| 25 Sept. | Sunny | 18° /10° | 55 mm | 5 | |
| 26 Sept. | Sunny | 20° /9° | 2.1 mm | 6 | |
| 27 Sept. | Mist | 20° /9° | 0 mm | 5 | |
| 28 Sept. | Partly cloudy | 20° /9° | 0 mm | 5 | |
| 29 Sept. | Mist | 21° /9° | 0 mm | 5 | |
| 30 Sept. | Partly cloudy | 22° /12° | 0 mm | 6 | |
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Important Notice
Our weather forecast for Ottawa 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 Ottawa forecast closer to your planned date for the most up-to-date weather information.
Ottawa in September - FAQ
What are the expected maximum and minimum temperatures in Ottawa during September?
Enjoy moderate daytime temperatures of up to 23° and cooler nights around 11°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Ottawa during September?
Expect minimal rainfall in Ottawa during September, with a total of 11.7 mm over approximately 5 days. This minimal precipitation is unlikely to significantly impact plans.
What are the typical wind conditions in Ottawa during September?
The average wind speed in Ottawa during September is 12 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Ottawa
Explore the daily rainfall trends and prepare for Ottawas September weather 💧
UV exposure in Ottawa during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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