Ottawa Weather in September
In September, Ottawa averages a high of 21°C (70°F) and a low of 10°C (50°F), based on 55 years of historical weather data from OTTAWA CDA.
21°C
Average high
70°F
10°C
Average low
50°F
36°C
Record high
96°F · 2002
-3°C
Record low
27°F · 2000
What to Expect in Ottawa in September
Typical September days in Ottawa reach 21°C (70°F) during the afternoon and cool to around 10°C (50°F) overnight. On average, measurable rain falls on about 40% of days this month. Over the past 55 years, September temperatures in Ottawa have ranged from a record high of 36°C (2002) down to a record low of -3°C (2000).
For a day-by-day look or other months, see the full Ottawa weather history.