Ottawa Weather in September

During September, Ottawa experiences high daytime temperatures of 27°C (81°F) and cooler nights around 14°C (57°F). Expect quite a bit of rainfall. Around 113 mm (4.4 in) is typical.

Rainfall in Ottawa in September

Typically, about 9 days will experience rainfall, with an average of 113 mm (4.4 in) for the month. When showers do arrive, they tend to be on the heavier side. Worth being prepared even if rain days are not that numerous.

Temperature in Ottawa in September

September in Ottawa brings typical temperatures with highs around 27°C (81°F) and lows of 14°C (57°F). This gives the month a fairly typical daily rhythm, with warmer afternoons and more comfortable nights. With lows of 14°C (57°F), nights are cool. If you're out after dark, an extra layer will keep you comfortable. The cooler air at night is also great for getting a good rest.

Sunshine in Ottawa in September

The city usually sees around 233 hours of sunlight, indicating many sunny days — a great month for sightseeing.

If you prefer dry days with pleasant temperatures, October typically offers the best circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.

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Check the conditions for any month of the year.

• January
• February
• March
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• May
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• September
• October
• November
• December

For a detailed overview over the year and the best time to visit the United States of America, check out our Ottawa's climate page.

Ottawa Temperature in September

Min Temperature 14°C (57°F)  

Max Temperature 27°C (81°F)  

Chance of Rain 30%  

Precipitation 113 mm (4.4 in)  

Rainy days 9 days  

Humidity 72% *  

Sunshine 233 hours *  

Percentage Sunshine 63% *  

* Data from: Topeka, the United States of America (59 KM, 37 Miles).

What to Wear in Ottawa in September

Warm weather calls for comfortable, breathable clothing in September. Cotton t-shirts, shorts, light dresses, and sandals are perfect. You might still want a light layer for evenings or air-conditioned places (for example buses). High rain levels are expected, so pack waterproof gear and an umbrella or poncho. Don't forget sun protection, sunglasses, sunscreen, and a hat. These are all good ideas with this much sunshine.

What To Do in Ottawa in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Swimming

9/10

Cycling

7/10

Walking

7/10

Camping

6/10

Outdoor sports

7/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit the United States of America, check out our Ottawa's climate page.

More climate data for Ottawa

Temperature Rainfall Sunshine Humidity

See the full Ottawa climate overview or explore weather in the United States of America.