May · Thailand
Best time to visit Koh Samui in May Weather, crowds & prices
Weather in Koh Samui in May
Average temperature 26°C, 135 mm of rain, about 28 days with 6+ hours of sunshine and 79% humidity — based on the five most recent complete years of ERA5 data (2021–2025).
May score
7.6/10
Ranked #8 of 12 months
- Avg temp
- 26°C
- Rainfall
- 135 mm
- Humidity
- 79%
- Days with 6h+ sun
- 28
- Crowd Density
- Quiet / Uncrowded
- Average Expenses
- $ · Budget Friendly ($)
May in Koh Samui scores 7.6/10 for beach and coastal travel - ranked #8 of 12. Expect around 26°C, 135 mm of rain, and roughly 28 days with 6+ hours of sunshine this month.
Koh Samui's ring road links Chaweng's beach, Bophut's Fisherman's Village, and the Big Buddha on the north coast.
May in Koh Samui — reliably good (8th best month)
May averages 26°C (79°F) and humidity near 79%, so the practical pattern is early mornings, a long midday break, and evenings back outside.
Monthly rainfall reaches 135 mm — wet for this destination — but about 28 days with 6+ hours of sunshine still break through, so keep one indoor fallback in the plan.
It scores 7.6/10 here, 8th of 12 months, against 9.3/10 in the destination's best month.
Pack the lightest breathable clothing you own, a hat, and more water than feels necessary, a proper rain shell rather than an umbrella.
Figure on low-season pricing, with crowds are light for this destination.
Flexible dates? March scores 1.7 points higher here — enough to change the trip.
Frequently asked
- What is the weather like in Koh Samui in May?
- In May, Koh Samui averages 26°C, 135 mm of rain, and about 28 days with 6+ hours of sunshine. Its climate-comfort score is 7.6/10.
- Is May a good time to visit Koh Samui?
- May earns a 7.6/10 climate-comfort score. Use the year-round chart to weigh the weather against your budget and crowd preferences.
- How much does it rain in Koh Samui in May?
- Expect about 135 mm of rain in May. Average humidity is 79% and there are about 28 days with 6+ hours of sunshine.
Curated in Koh Samui
Tickets & experiences
Things to do in Koh Samui
Koh Samui, Thailand. Live activities and tours from GetYourGuide, matched to this destination.