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Canada weather

Weather in Ottawa for September 2025

Your guide to Ottawa weather in September - trends and predictions

    Temperatures

  • 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.

    • Rain 🌧️

  • Ottawa experiences moderate rainfall in September, with an average of 6 rainy days and a total precipitation of 75.7 mm.

    • More

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Average dry days
24
Dry days
Average rainy days
6
Rainy days
Average snowy days
0
Snow days
Average temperatures
22°/11°
Temperatures
Average wind speed
13 km/h
Avg max wind
Average humidity
74 %
Avg humidity

Ottawa Weather September

Move between months or click on a day
August
October
Sun.Mon.Tue.Wed.Thu.Fri.Sat.
1
Overcast
24°
2
Overcast
22°
3
Mist
25°
4
Overcast
27°
5
Mist
28°
6
Thundery outbreaks possible
28°
7
Thundery outbreaks possible
23°
8
Light rain
16°
9
Cloudy
21°
10
Overcast
21°
11
Overcast
23°
12
Fog
24°
13
Mist
21°
14
Mist
21°
15
Partly cloudy
24°
16
Partly cloudy
25°
17
Patchy rain possible
25°
18
Patchy light drizzle
23°
19
Thundery outbreaks possible
24°
20
Overcast
21°
21
Mist
21°
22
Overcast
22°
23
Mist
19°
24
Mist
22°
25
Sunny
18°
26
Sunny
20°
27
Mist
20°
28
Partly cloudy
20°
29
Mist
21°
30
Partly cloudy
22°

Temperatures trend during September in Ottawa

See the weather trend as well as the moving average line

September weather in Ottawa day by day

Click on a date for more information
August October
Date Weather Temperatures Rain UV More
1 Sept. Overcast
Overcast
 24° /10° 2.9 mm 6
2 Sept. Overcast
Overcast
 22° /10° 0 mm 5
3 Sept. Mist
Mist
 25° /10° 0 mm 7
4 Sept. Overcast
Overcast
 27° /14° 0 mm 7
5 Sept. Mist
Mist
 28° /15° 0 mm 7
6 Sept. Thundery outbreaks possible
Thundery outbreaks possible
 28° /15° 0.2 mm 6
7 Sept. Thundery outbreaks possible
Thundery outbreaks possible
 23° /12° 8.1 mm 5
8 Sept. Light rain
Light rain
 16° /10° 2.2 mm 4
9 Sept. Cloudy
Cloudy
 21° /7° 0 mm 5
10 Sept. Overcast
Overcast
 21° /9° 0 mm 5
11 Sept. Overcast
Overcast
 23° /9° 0 mm 5
12 Sept. Fog
Fog
 24° /13° 0.1 mm 6
13 Sept. Mist
Mist
 21° /12° 0.1 mm 6
14 Sept. Mist
Mist
 21° /10° 0 mm 5
15 Sept. Partly cloudy
Partly cloudy
 24° /10° 0 mm 6
16 Sept. Partly cloudy
Partly cloudy
 25° /12° 0 mm 7
17 Sept. Patchy rain possible
Patchy rain possible
 25° /13° 0.6 mm 6
18 Sept. Patchy light drizzle
Patchy light drizzle
 23° /12° 0.8 mm 5
19 Sept. Thundery outbreaks possible
Thundery outbreaks possible
 24° /14° 0 mm 6
20 Sept. Overcast
Overcast
 21° /11° 0 mm 5
21 Sept. Mist
Mist
 21° /9° 0 mm 5
22 Sept. Overcast
Overcast
 22° /9° 0 mm 5
23 Sept. Mist
Mist
 19° /11° 3.8 mm 5
24 Sept. Mist
Mist
 22° /12° 0 mm 5
25 Sept. Sunny
Sunny
 18° /10° 55 mm 5
26 Sept. Sunny
Sunny
 20° /9° 2.1 mm 6
27 Sept. Mist
Mist
 20° /9° 0 mm 5
28 Sept. Partly cloudy
Partly cloudy
 20° /9° 0 mm 5
29 Sept. Mist
Mist
 21° /9° 0 mm 5
30 Sept. Partly cloudy
Partly cloudy
 22° /12° 0 mm 6
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.
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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 11°. 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 75.7 mm spread over approximately 6 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 💧

UV exposure in Ottawa during September

Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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Location coordinates Where is Ottawa?

Get accurate weather forecasts for Ottawa, located at latitude 45.411 and longitude -75.698. Stay updated with localized weather information tailored for Ottawa.

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