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Climate · Ottawa

Ottawa in September

Warm and damp, as the days shorten.

Typical weather, averaged over 30 years

September in Ottawa is warm: highs near 74°F, lows near 55°F. Rain falls on about two days a week, and the days shorten by 1 hour 9 minutes from the first week to the last.September in Ottawa is warm: highs near 23°C, lows near 13°C. Rain falls on about two days a week, and the days shorten by 1 hour 9 minutes from the first week to the last.

High
74°F23°Caverage
Low
55°F13°Caverage
Wet days
2a week · 32% of days
Daylight
12h 26mon average

Is September a good time to visit Ottawa?

Yes. September is one of Ottawa's best months (June, or August to September).

How we judge it: every month is scored on how close its typical high comes to the range from 70°F to 80°F, how mild its nights are, and how rarely it rains. The best months are the run of months that scores best.How we judge it: every month is scored on how close its typical high comes to the range from 21°C to 27°C, how mild its nights are, and how rarely it rains. The best months are the run of months that scores best.

How September sits in the year

week by week

Temperature

Highs near 74°F in September, against 28°F to 82°F through the year.Highs near 23°C in September, against -2°C to 28°C through the year.

Chance of a wet day

32% of days in September, against 32% to 43% through the year.

Cloud cover

42% cover in September, against 42% to 70% through the year.

Daylight

12h 26m in September, against 8h 46m to 15h 36m through the year.

Week by week, lightly smoothed, with September shaded. The olive line marks the best months. Hover or tap a week for its figures.

Either side

  1. August80°27°low 62°low 17°3 wet days a weekRain on about three days a week.
  2. September74°23°low 55°low 13°2 wet days a weekRain on about two days a week.
  3. October62°17°low 45°low 7°3 wet days a weekRain on about three days a week.

Where Ottawa sits, in September

America/Toronto
this place
typical high in September 40°F4°C95°F35°C
Sunrise, mid-September
6:40 AMsets 7:16 PM
Above the sea
70 mlow-lying
Latitude
45.4°Nnorthern hemisphere
Nearest of ours
Mont-Tremblant115 km north-east

The land around Ottawa, shaded by its typical high in September, the planning map's own layer. Hover the map for the figure at that spot; tap it on a phone. Clock times are local, for the 15th.

Elsewhere in Canada in September

high · low · wet days
See September on the planning mapThe whole year in Ottawa

Typical weather, averaged over 30 years (1995–2024), from the 11 km grid square nearest Ottawa. Temperatures are adjusted against 66 weather stations: daytime highs read about 3.1°F cold in the source data and are raised to match.Temperatures are adjusted against 66 weather stations: daytime highs read about 1.7°C cold in the source data and are raised to match. Daylight is calculated from latitude. Charts are lightly smoothed week to week; the figures in the table are not. Source: Copernicus ERA5-Land reanalysis; cloud cover from NASA's MERRA-2 reanalysis, on a coarser grid of about 50 km. Contains modified Copernicus Climate Change Service information 2026; neither the European Commission nor ECMWF is responsible for any use of it. These are averages, not a forecast.

Daylight is calculated from latitude. Charts are lightly smoothed week to week; the figures in the table are not.

Source: Copernicus ERA5-Land reanalysis; cloud cover from NASA's MERRA-2 reanalysis, on a coarser grid of about 50 km. Contains modified Copernicus Climate Change Service information 2026; neither the European Commission nor ECMWF is responsible for any use of it. These are averages, not a forecast.