How did Calgary's September temperatures compare to the long-term average?

Calgary's September 2025 temperatures were far above the long-term average, making it the warmest September ever recorded for the city. The mean temperature in Calgary for the month was 16.41°C, surpassing the previous record of 15.96°C set in 1938. For context, Calgary’s typical mean temperature for September is around 12°C, and daytime highs usually hover near 16°C. This year, daytime highs often exceeded 20°C, and the city experienced more days with temperatures above the seasonal norm.theweathernetwork+4

This unprecedented warmth, combined with record-low precipitation, established September 2025 as an extreme outlier compared to historical climate norms in Calgary.cbc+1

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