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Ottawa Weather in August
In Ottawa, August brings high daytime temperatures around 26°C (79°F), with nights cooling to 14°C (57°F). Expect quite a bit of rainfall this month.
Rainfall in Ottawa in August
Historically, the month has about 11 days of rain, averaging 94 mm (3.7 in) in total. The rain this month tends to fall in heavier spells rather than light drizzle. When it rains, showers can be significant.
Temperature in Ottawa in August
The temperature in Ottawa in August is excellent. Daytime highs reach 26°C (79°F), with nights dropping to 14°C (57°F). Experience the summer season in August. Overall, the month follows a fairly predictable daily temperature pattern. Nights cool down to 14°C (57°F), so a light jacket or extra layer is useful once the sun goes down. On the plus side, the cooler nights make for comfortable sleeping conditions.
Sunshine in Ottawa in August
With approximately 251 hours of sunshine, the days are filled with clear skies. It makes it a perfect month for being outside.If you favor pleasant temperatures and minimal rainfall, August is one of the best months to visit Ottawa.
Ottawa Temperature in August
Min Temperature
14°C (57°F)
Max Temperature
26°C (79°F)
Chance of Rain
38%
Precipitation
94 mm (3.7 in)
Rainy days
11 days
Humidity
54%
Sunshine
251 hours
Percentage Sunshine
57%
Ottawa Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Ottawa - and find the best time to visit.
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Ottawa typically stay consistent throughout August, with daily highs averaging around 26°C (79°F). Nights are pleasant, with lows typically ranging from 12°C (54°F) to 16°C (61°F).
Average temperatures in August
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in August
Historical weather records for Ottawa in August
Browse day-by-day weather records for Ottawa spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Ottawa historical weather extremes in August
Based on weather observations in Ottawa between 1976 and 2026, these are the recorded extremes during August.
- The hottest August day on record in Ottawa reached 36°C (97°F) (August 9, 2001).
- Ottawa experienced its chilliest August day on August 28, 1986, reaching only 14°C (57°F).
- Nighttime temperatures dropped to 1°C (34°F) on August 16, 1977, marking the coldest August night on record.
Best Places in Canada in August
Find out more about the weather in Canada and which places have the best travel conditions in this month. See all of Canada in August →
perfect weather
pleasant
tolerable
unpleasant
poor
Perfect weather is subjective. On this map perfect weather has been defined with temperatures between 20°C (68°F) and 29°C (84°F) and not too much precipitation (less than 90 mm (3.5 in) a month).
What to Wear in Ottawa in August
Warm weather calls for comfortable, breathable clothing in August. 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. And with plenty of sunshine hours, don’t forget sunglasses, sunscreen, and maybe a sun hat.
What To Do in Ottawa in August
We rated the following activities from 1 (least suitable) to 10 (best) to do.
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Swimming9/10 -
Cycling7/10 -
Walking7/10 -
Camping8/10 -
Outdoor sports7/10
Ottawa 3-Day Forecast
More climate data for Ottawa
Temperature Rainfall Sunshine Humidity
See the full Ottawa climate overview or explore weather in Canada.
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Where to go in August - average daytime high across popular destinations.
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