Koh Samui, Thailand
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Koh Samui

August beach and weather guide

Based on 5 years of historical ERA5 climate data

Photo by Marius Kriz on Unsplash

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August beach conditions — historical average

Excellent
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📉 Our data shows more unsettled conditions in 2024-2025 compared to 2021-2022 for this destination and time of year
28.5°C Temp
30.9°C Sea temp
9.4 Rain days
9.9h Sunshine hrs
76.8% Humidity
100%

Reliable conditions

5 of 5 years were good

Year by year — mid August

2025 Excellent 27.5°C · 9 rainy days · 8.1h sun
2024 Good 28.3°C · 13 rainy days · 11.2h sun
2023 Excellent 29.2°C · 10 rainy days · 10.6h sun
2022 Excellent 28.9°C · 7 rainy days · 9.8h sun
2021 Excellent 28.4°C · 8 rainy days · 9.8h sun

Other months in Koh Samui

January February March July August September

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About Koh Samui in August

Based on 5 years of ERA5 historical climate data, August in Koh Samui has historically been excellent for a beach holiday. Average temperatures of 28.5°C with sea temperatures around 30.9°C and 9.4 rainy days on average.

5 of the last 5 years had good beach conditions during this period. This data uses ERA5 reanalysis records — real historical measurements, not generalised averages.

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