Koh Samui Weather in September

September in Koh Samui typically sees daytime highs of 30°C (86°F) and nighttime lows of 27°C (81°F). Rainfall is also possible this month, so it's worth packing an umbrella.

Rainfall in Koh Samui in September

Historically, approximately 18 days this month are expected to have rain, averaging 156 mm (6.1 in). Wet weather is a regular and significant part of this month. Frequent days of rain combined with high totals means proper waterproofs are worth packing.

Temperature in Koh Samui in September

In September, Koh Samui gets high temperatures, with highs of 30°C (86°F). Nights cool to around 27°C (81°F). Conditions stay fairly consistent through the month, making it easier to plan what to wear. Nights are warm at 27°C (81°F), which can make sleeping uncomfortable. Keeping windows open or using a fan can help. A cold shower before bed is also a good way to cool down.

Sunshine in Koh Samui in September

You can expect a moderate amount of sunlight, with approximately 145 hours. This means a pleasant mix of sun and overcast.

Average water temperature in September

At 29°C (84°F), the water feels bath-warm. Fine for swimming, but those looking for a cooling swim may be a bit disappointed.

If you prefer dry days with pleasant temperatures, January and February typically offer the best circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.