Ottawa
September
Weather in Ottawa for September 2026
Your guide to Ottawa weather in September - trends and predictions
Until now, September 2026 in Ottawa has been nearly identical to the historical average, with a temperature of 23 °C (showing only a slight deviation of 0.3 °C).
The forecast for the next days in Ottawa predicts a temperature of 16.9 °C, which is cooler than the historical average.
In general, the average temperature in Ottawa at the beginning of September is 24.4 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 19.1 °C by the end of September.
With an average of 4 rainy days, Ottawa experiences minimal rainfall in September.
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Temperatures
Rain 🌧️
More
26
Dry days
4
Rainy days
0
Snow days
22°/12°
Temperatures
13 km/h
Avg max wind
71 %
Avg humidity
Ottawa Weather September
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Temperatures trend during September in Ottawa
See the weather trend as well as the moving average line
September weather in Ottawa day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| 1 Sept. |  Overcast | 24° /13° | 55.9 mm | 5 | |
| 2 Sept. | Overcast | 24° /13° | 3.3 mm | 5 | |
| 3 Sept. |  Sunny | 26° /13° | 12.7 mm | 7 | |
| 4 Sept. | Sunny | 26° /14° | 1.4 mm | 7 | |
| 5 Sept. |  Mist | 25° /13° | 0.1 mm | 6 | |
| 6 Sept. | Overcast | 24° /14° | 0.1 mm | 6 | |
| 7 Sept. |  Thundery outbreaks possible | 22° /11° | 4.1 mm | 5 | |
| 8 Sept. |  Light rain | 18° /11° | 12.7 mm | 4 | |
| 9 Sept. |  Cloudy | 22° /9° | 4.6 mm | 4 | |
| 10 Sept. | Overcast | 22° /9° | 0 mm | 6 | |
| 11 Sept. | Overcast | 23° /10° | 0 mm | 5 | |
| 12 Sept. | Overcast | 23° /10° | 0.3 mm | 5.2 | |
| 13 Sept. |  Light rain shower | 23° /14° | 2.3 mm | 4.1 | |
| 14 Sept. | Sunny | 17° /7° | 0 mm | 5 | |
| 15 Sept. | Overcast | 16° /6° | 1 mm | 4 | |
| 16 Sept. | Overcast | 22° /13° | 0.2 mm | 5 | |
| 17 Sept. | Overcast | 14° /10° | 0 mm | 3 | |
| 18 Sept. | Patchy rain possible | 11° /9° | 20.3 mm | 3 | |
| 19 Sept. | Light rain shower | 11° /8° | 8.8 mm | 3 | |
| 20 Sept. | Sunny | 16° /8° | 0 mm | 5 | |
| 21 Sept. | Sunny | 18° /7° | 0 mm | 5 | |
| 22 Sept. | Sunny | 19° /8° | 0 mm | 5 | |
| 23 Sept. | Overcast | 20° /12° | 5.8 mm | 4 | |
| 24 Sept. | Patchy rain possible | 13° /5° | 0.3 mm | 3 | |
| 25 Sept. | Sunny | 14° /2° | 0 mm | 4 | |
| 26 Sept. | Sunny | 21° /11° | 1.4 mm | 5 | |
| 27 Sept. | Mist | 20° /9° | 0 mm | 4 | |
| 28 Sept. |  Partly cloudy | 22° /11° | 0 mm | 5 | |
| 29 Sept. | Mist | 23° /10° | 0 mm | 5 | |
| 30 Sept. | Partly cloudy | 21° /11° | 0 mm | 5 | |
| Next | |||||
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.
Change Month
Ottawa in September - FAQ
What are the expected maximum and minimum temperatures in Ottawa during September?
Enjoy moderate daytime temperatures of up to 22° and cooler nights around 12°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Ottawa during September?
Moderate rainfall is anticipated in Ottawa during September, with a total of 76.4 mm spread over approximately 4 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in Ottawa during September?
The average wind speed in Ottawa during September is 13 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 💧
Typically, Ottawa has 4 rainy days in September with a total of 76.4 mm of rainfall.
UV exposure in Ottawa during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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