Month by month
| Month | Afternoon | Sea | Rain | Verdict |
|---|---|---|---|---|
| January | 28.2 °C | 28.1 °C | 15 days | Possible, with trade-offs |
| February | 28.9 °C | 28.3 °C | 10 days | Ideal — one of the best times of year |
| March | 30.4 °C | 29.2 °C | 9 days | Ideal — one of the best times of year |
| April | 31.1 °C | 30.4 °C | 13 days | Ideal — one of the best times of year |
| May | 30.9 °C | 30.8 °C | 22 days | Unfavourable season |
| June | 30.5 °C | 30.4 °C | 18 days | Unfavourable season |
| July | 30 °C | 29.9 °C | 20 days | Unfavourable season |
| August | 30 °C | 29.7 °C | 21 days | Unfavourable season |
| September | 29.2 °C | 29.5 °C | 22 days | Unfavourable season |
| October | 28.5 °C | 29.3 °C | 27 days | Unfavourable season |
| November | 28.3 °C | 28.9 °C | 26 days | Unfavourable season |
| December | 27.9 °C | 28.1 °C | 20 days | Unfavourable season |
Before you go
Three things to check once you have picked your dates.
Entry
Entry rules depend on your nationality and change often. Check them before booking.
Safety
Some areas advised against
The country is open, but parts should be avoided.
Official advice updated 30 June 2026
Health
Recommended vaccinations, water quality, mosquitoes: advice depends on the country and the season. Some vaccines need time before departure.
Beau Fixe is not a safety or health authority. These notes summarise public advisories and link to their source; only the competent authorities are authoritative. Alert levels: Foreign, Commonwealth & Development Office (gov.uk), Open Government Licence v3.0.
FAQ
Can you swim in Ko Samui in August?
The sea averages 29.7°C in August — yes, pleasant swimming.
How hot is Ko Samui in August?
Expect 30°C in the afternoon and 26.1°C at night, averaged over the last 10 years.
Does it rain a lot in Ko Samui in August?
Around 21 days with rain (≥ 1 mm) in the month — 66% of days.