In September, Ko Samui typically sees daytime highs of 30.6°C and overnight lows around 24.4°C. Compared to the annual average high of 30.3°C, September runs +0.3°C.
September in Ko Samui averages a daytime high of 30.6°C and an overnight low of 24.4°C.
September runs +0.3°C compared to Ko Samui's annual average high of 30.3°C, ranking #7 of 12 months by warmth.
Plan for daytime highs near 30.6°C and cooler evenings around 24.4°C.