Ottawa weather in August 2025

Expect daytime maximum temperatures of 25°C in Ottawa, Ontario in August based on long-term weather averages. There are 8 hours of sunshine per day on average with 11 days with some rainfall and typically 86 mm of rainfall in the month.

  • 25°C maximum daytime temperature in August in Ottawa25
    25°C max day temperature
  • 8 hours of sunshine per day
  • 11 days with some rainfall in August in Ottawa11
    11 days with some rainfall
  • 14°C minimum night-time temperature in August in Ottawa14
    14°C min night temperature
  • 14 hours of daylight per day in August in Ottawa14
    14 hours of daylight per day
  • No heat & humidity in August in Ottawa0
    No heat & humidity
  • 86 mm monthly rainfall in August in Ottawa86
    86 mm of monthly rainfall
  • UV (maximum) index 7 (High) in August in Ottawa7
    7 (High) UV index

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The August weather guide for Ontario (Ottawa) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm)  |  Imperial (°F / inches)

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More about Ontario

How hot is it in Ottawa in August?

Daytime temperatures usually reach 25°C in Ottawa in August with no heat and humidity, falling to 14°C at night.

How sunny is it in Ottawa in August?

There are normally 8 hours of bright sunshine each day in Ottawa in August - that's 55% of daylight hours.

Does it rain in Ottawa in August?

There are usually 11 days with some rain in Ottawa in August and the average monthly rainfall is 86mm.

Ottawa August sunrise & sunset times

Browse the sunrise and sunset times for Ottawa in August 2025. Select a month to view Ottawa sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Friday, 1st August 2025 04:47 19:30
Saturday, 16th August 2025 05:05 19:08
Sunday, 31st August 2025 05:23 18:42

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