In September, Keflavik typically sees daytime highs of 10.0°C and overnight lows around 6.0°C. Compared to the annual average high of 6.8°C, September runs +3.1°C.
September in Keflavik averages a daytime high of 10.0°C and an overnight low of 6.0°C.
September runs +3.1°C compared to Keflavik's annual average high of 6.8°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 10.0°C and cooler evenings around 6.0°C.