In September, Dun Laoghaire typically sees daytime highs of 16.6°C and overnight lows around 10.1°C. Compared to the annual average high of 12.7°C, September runs +3.9°C.
September in Dun Laoghaire averages a daytime high of 16.6°C and an overnight low of 10.1°C.
September runs +3.9°C compared to Dun Laoghaire's annual average high of 12.7°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 16.6°C and cooler evenings around 10.1°C.