In September, Rotterdam typically sees daytime highs of 18.5°C and overnight lows around 10.4°C. Compared to the annual average high of 13.0°C, September runs +5.5°C.
September in Rotterdam averages a daytime high of 18.5°C and an overnight low of 10.4°C.
September runs +5.5°C compared to Rotterdam's annual average high of 13.0°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 18.5°C and cooler evenings around 10.4°C.