Ko Samui weather in May
May in Ko Samui: sweltering, rainy, with clean air — a great time to visit.
#7 of 12 months in Ko Samui · #363 of 604 destinations to visit in May · comfort 79/100 (tier B)
Updated June 2026 · climate normals from ERA5 reanalysis
Ko Samui climate normals — May
| Daytime high | 30°C / 87°F | 🔥 sweltering |
|---|---|---|
| Nighttime low | 28°C / 82°F | |
| Feels like (high) | 37°C / 99°F | |
| Rainfall | 116 mm / 4.6 in | 🌧 rainy |
| Rainy days | 18 days | |
| Humidity | 78% | 💦 very humid |
| Dew point | 25°C / 76°F | |
| Sunshine | 10.4 h/day | |
| Daylight | 12.6 h | |
| Wind | 21 km/h / 13 mph | |
| Air quality (US AQI) | 35 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Where is Ko Samui?
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Ko Samui in May — FAQ
- Is May a good time to visit Ko Samui?
- May in Ko Samui: sweltering, rainy, with clean air — a great time to visit. It ranks #7 of 12 months for Ko Samui on SeasonMap's comfort score (79/100).
- What is the weather like in Ko Samui in May?
- In May, Ko Samui averages a daily high of 30.4°C and a low of 27.7°C, with about 116.2 mm of rain over roughly 18 rainy days.
- What is the air quality in Ko Samui in May?
- Ko Samui has a mean US Air Quality Index of about 35 in May.