In September, Basel typically sees daytime highs of 20.1°C and overnight lows around 9.9°C. Compared to the annual average high of 13.9°C, September runs +6.1°C.
September in Basel averages a daytime high of 20.1°C and an overnight low of 9.9°C.
September runs +6.1°C compared to Basel's annual average high of 13.9°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 20.1°C and cooler evenings around 9.9°C.