Weather in Ottawa in August 2025
Average weather
Average temperature in Ottawa in August
Going from a maximum of +82°F during the day to a minimum of +46°F during the night, the temperature in August averages around +75°F.
The average maximum temperature goes up 0% by the end of the month, compared with the beginning of the month, from +72°F to +72°F.
Is Ottawa warm or cold in August?
Ottawa is typically warm in August.
Maximum temperatures go down compared to the previous month from +81°F to +77°F. The minimum temperature also goes down from +61°F to +59°F.
It’s generally warm, but pack a long-sleeve shirt for evenings.
August is one of the warmest months in Ottawa, here is the comparison with other months:
Climate in Ottawa in August
| July | August | September | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +81°F | +77°F | +70°F | ||||
| Min. temperature | ||||||
| +43°F | +39°F | +27°F | ||||
| Max. temperature | ||||||
| +97°F | +97°F | +95°F | ||||
| Rainfall | ||||||
| 91 mm | 85 mm | 88 mm | ||||
| Wind | ||||||
| 2 m/s | 2 m/s | 2 m/s | ||||
| Humidity | ||||||
| 69% | 72% | 75% | ||||
| Air pressure | ||||||
| 1012 HPa | 1014 HPa | 1016 HPa | ||||
| Sunny days | ||||||
| 3 | 4 | 4 | ||||
| Cloudy days | ||||||
| 11 | 11 | 12 | ||||
| Rainy days | ||||||
| 11 | 12 | 12 | ||||
| Snowy days | ||||||
| 0 | 0 | 0 | ||||
August weather is still as good as in July. It’s getting colder in August. From +81°F in the day, the average maximum temperature lowers to +77°F. As August arrives, the amount of rainfall goes down. On average, the rainfall volume decreases from 91 mm to 85 mm. Humidity rises from 69% to 72%. The average wind speed doesn’t change much during August, staying around 2 m/s. The good news is there are likely to be more sunny days in August, from 3 to 4.
Next month (September) brings a further decline in the weather.
Wind
The average wind speed is 3 m/s getting up to 6 m/s which is a medium breeze. You can feel it, especially getting out of the water.
The average wind speed in Ottawa is gradually increasing during August, going from 3 m/s to 3 m/s over the course of the month.
Rain
How was the weather last August in Ottawa?
Climate Change Over the Years
The climate in Ottawa in August has not changed that much over the last 43 years.
The average temperature was the lowest in 1992 (+51°F) and the highest in 2012 (+56°F). The driest year was 1985 with only 469 mm of rainfall, and the wettest year was 2017 with 1378 mm.
FAQ
Is August a good time to visit Ottawa?
Can you sunbathe in Ottawa in August?
Is Ottawa rainy in August?
Is it sunny in Ottawa in August?
Other cities in Canada
Monthly weather in Ottawa
Source of the data
For this page, we’ve looked at the typical weather in Ottawa, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.