Calgary Weather in September
In September, Calgary averages a high of 18°C (64°F) and a low of 5°C (40°F), from 54 years of daily records (1971–2026).
18°C
Average high
64°F
5°C
Average low
40°F
33°C
Record high
92°F · September 23, 2009
-7°C
Record low
19°F · September 29, 1985
What September Is Like in Calgary
- September 2025 was the warmest September in 54 years of records, 5.1°C (9.3°F) above the long-run average.
- September in Calgary has become 2.1°C (3.7°F) warmer on average: the 2011–2025 average against 1970–1989.
- 5 of the 10 warmest Septembers on record in Calgary have come since 2011.
- The coldest September reading, -7°C (19°F) on September 29, 1985, has not been matched in 41 years.
At least 1 mm of rain falls on 20% of September days, and the month averages 37 mm in total.
Warmest: 2025 (24.6°C)Latest: 2025 (24.6°C)10-year averageLong-run average (18.0°C)
Look Up a Day in September
See the weather in Calgary on any September date, year by year.
Source: NOAA GHCN-Daily, Calgary Int'L Cs (1999–2026); University Of Calgary (1971–1990); Calgary Int'L A (1980–2012); Calgary Glenmore Dam (1971–1978). Averages cover 1971–2026. How we compute this