Weather in Koh Samui in May
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Compare car hire prices → Affiliate link — we earn a commission at no extra cost to youMay in Koh Samui is hot, with average highs of 31.0°C and lows of 26.5°C. It is fairly wet (20 rainy days on average), with roughly 10.4 hours of sunshine a day. This is peak season for good reason — conditions are close to ideal. For the complete picture, see the best time to visit Koh Samui — every month compared. Once you know when to go, find your Koh Samui packing list at 247PackingList.
Get ready for Koh Samui in May
Search flights to Koh Samui
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Search Flights →Lightweight travel clothing
Lightweight, breathable clothing and a compact travel umbrella are essential in this climate.
Check Price →What to pack for Koh Samui in May
- Lightweight, breathable clothing
- High SPF sunscreen
- Sunglasses
- Sun hat
- Reusable water bottle
- Compact travel umbrella
- Waterproof jacket
- Quick-dry clothing
Compare all months in Koh Samui
| Month | High | Rain | Rating |
|---|---|---|---|
| January | 28.5°C | 43.1mm | 10/10 |
| February | 29.0°C | 58.2mm | 10/10 |
| March | 30.5°C | 36.5mm | 10/10 |
| April | 31.1°C | 106.9mm | 9/10 |
| May | 31.0°C | 134.5mm | 9/10 |
| June | 30.6°C | 102.4mm | 9/10 |
| July | 30.0°C | 149.9mm | 9/10 |
| August | 30.4°C | 114.2mm | 9/10 |
| September | 29.2°C | 196.8mm | 9/10 |
| October | 28.5°C | 244.4mm | 8/10 |
| November | 28.1°C | 323.1mm | 8/10 |
| December | 27.9°C | 161.7mm | 9/10 |
Full month-by-month guide: best time to visit Koh Samui →
For facts about Thailand — currency, language and dialling code — see our Thailand country guide at 247CountryInfo. Travellers also find it useful to keep a Koh Samui travel guide to hand. Check clothing sizes in Thailand before you shop.
Frequently Asked Questions
Is May a good time to visit Koh Samui?
May rates 9/10 for visiting Koh Samui — excellent time to visit. Expect average highs of 31.0°C, 134.5mm of rain across the month and about 10.4 hours of daily sunshine.
What is the temperature in Koh Samui in May?
In May, Koh Samui has average highs of 31.0°C (87.8°F) and average lows of 26.5°C (79.7°F).
Does it rain in Koh Samui in May?
Some rain is likely. Koh Samui averages 134.5mm across about 20 rainy days in May, so a light waterproof layer is worth packing.
What should I wear in Koh Samui in May?
For Koh Samui in May (31.0°C highs / 26.5°C lows), pack lightweight, breathable clothing plus high spf sunscreen, sunglasses, sun hat.
More essentials for Koh Samui in May
Packing cubes
Keep the bag organised whatever the weather — compression cubes for every size.
Check Price →Travel first aid kit
Compact TSA-friendly kit for peace of mind wherever you travel.
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Climate data sourced from Open-Meteo (open source, open data licence). Monthly averages calculated from 2020–2023 historical data. Weather can be unpredictable — always check a live forecast before travelling.