Koh Samui in May
In May, Koh Samui averages 31°C (87°F) during the day and 27°C (80°F) at night, with frequent rain — about 29 days of the month see precipitation (130 mm total).
ShoulderConditions are warm and beach-friendly. Expect daily rain or showers, often in heavy bursts.
May is one of the wetter and less comfortable months in Koh Samui. If your dates are flexible, consider a different time of year.
How May compares to the rest of the year in Koh Samui
May is one of the warmest months in Koh Samui (2nd of 12) and one of the wettest months (2nd of 12). Daytime temperature runs 1°C above the annual average (29°C). May runs roughly the same as April (31°C) and stays flat into June.
May sunrise & sunset in Koh Samui
Times shown for Koh Samui local time (Asia/Bangkok), calculated for the 15th of May. They shift by a few minutes day to day across the month.
Photography light in Koh Samui — May
Golden-hour and blue-hour windows for the 15th of May, in Koh Samui's local time. Use these for soft warm light (golden) or cool architectural twilight (blue).
📅 When to book — Koh Samui in May
Travel writers usually only tell you when to go. Here's when to book flights and lodging for the best mix of price and availability, based on May's tier (Shoulder) and Koh Samui's popularity.
Crowds & pricing — May in Koh Samui
Koh Samui is in a shoulder season month — fewer crowds, slightly lower prices, and a calmer atmosphere than peak weeks. Most major sights stay open with normal hours, though a handful of seasonal restaurants or boat trips may run reduced schedules. Many regulars consider these months the best time to visit because you trade a small amount of weather reliability for a much more pleasant on-the-ground experience.
Sun & mosquito risk — May in Koh Samui
UV is a clear-sky sea-level estimate — clouds, altitude, and reflective surfaces (snow, water) shift it ±30%. Mosquito risk is climate-derived only; for current disease advisories (dengue, malaria, zika) check the CDC or WHO travel pages before your trip.
Sea temperature in Koh Samui — May
Across the year Koh Samui's sea swings from 28.6°C (January) to 32.1°C (May) — May sits at 32.1°C.
Koh Samui in other months
| Month | Avg high | Avg low | Rainfall | Rain days | Snow days |
|---|---|---|---|---|---|
| January | 28°C / 82°F | 25°C / 76°F | 113 mm | 24 | — |
| February | 28°C / 83°F | 25°C / 77°F | 33 mm | 17 | — |
| March | 30°C / 86°F | 26°C / 78°F | 32 mm | 17 | — |
| April | 31°C / 87°F | 27°C / 80°F | 107 mm | 23 | — |
| May | 31°C / 87°F | 27°C / 80°F | 130 mm | 29 | — |
| June | 30°C / 86°F | 27°C / 80°F | 96 mm | 27 | — |
| July | 30°C / 86°F | 26°C / 79°F | 115 mm | 28 | — |
| August | 30°C / 86°F | 26°C / 79°F | 94 mm | 28 | — |
| September | 29°C / 84°F | 26°C / 78°F | 172 mm | 29 | — |
| October | 28°C / 83°F | 25°C / 77°F | 234 mm | 31 | — |
| November | 28°C / 82°F | 25°C / 77°F | 274 mm | 29 | — |
| December | 28°C / 82°F | 25°C / 76°F | 182 mm | 24 | — |
Other cities with similar May weather
🌍 See the full ranked list of climate twins for Koh Samui in May →
Frequently asked questions
How hot is Koh Samui in May?
In May, Koh Samui averages a high of 31°C (87°F) and a low of 27°C (80°F) — generally hot.
Does it rain a lot in Koh Samui in May?
May is quite rainy in Koh Samui, with about 29 rainy days on average.
Is May a good time to visit Koh Samui?
May is hot but on the rainy side. It suits travelers who are comfortable with hot weather; check the month-by-month ranking to compare it against the rest of the year.
What should I pack for Koh Samui in May?
Pack lightweight, breathable clothing, sunglasses and sunscreen, plus a compact umbrella or rain jacket. See the full May packing list for Koh Samui for a complete, climate-based checklist.
Check the live 10-day forecast and sunrise/sunset.