Koh Samui's rainy season runs on a different clock from most of Thailand. The Gulf side is wettest from October to December, when the rest of the country is drying out. Pack for heat every month, and for downpours late in the year.
Koh Samui weather by month
Daily high and low (°C), and days with rainSee the numbers
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| High | 30°C86°F | 29°C84°F | 30°C86°F | 32°C90°F | 34°C93°F | 35°C95°F | 34°C93°F | 34°C93°F | 32°C90°F | 32°C90°F | 30°C86°F | 30°C86°F |
| Low | 25°C77°F | 25°C77°F | 27°C81°F | 27°C81°F | 27°C81°F | 26°C79°F | 26°C79°F | 26°C79°F | 26°C79°F | 26°C79°F | 25°C77°F | 25°C77°F |
| Rain days | 13 | 14 | 12 | 12 | 20 | 18 | 17 | 17 | 18 | 23 | 24 | 17 |
Season by season
Dry season
January–AprilThe best beach weather. Highs are 29–32°C (84–90°F) and lows 25–27°C (77–81°F). Rain days still run 12–14 a month, but showers are mostly short. Pack swimwear, light cotton or linen, a hat and sun protection.
Hot season
May–SeptemberHottest stretch of the year. June peaks at 35°C (95°F), and May, July and August reach 34°C (93°F). Rain days run 17–20 a month, often as afternoon storms. Bring breathable clothes, a refillable water bottle and something to cool you down.
Monsoon season
October–DecemberSamui's wet season. November averages 24 rain days and October 23, with highs of 30–32°C (86–90°F). Seas can get rough, and some boat trips to Ang Thong Marine Park are cancelled. Pack a rain jacket, waterproof bags and sandals that dry fast. These numbers are from the Ko Samui station, 9 km (5.6 miles) away; conditions are similar across the island.
What to bring to Koh Samui
0 of 23 packedThai sockets vary between Type A, B, C and O, so a universal adapter covers whatever your room has.
- Nite Ize RunOff Waterproof Packing CubeBags & Luggage
November averages 24 rain days, and a waterproof cube keeps clothes dry on boat trips and scooter rides.
- Bearwind S40 Portable Handheld Turbo FanTech & Power
With June highs of 35°C (95°F) and humid nights, a handheld fan earns its space.
- Sawyer 20% Picaridin Insect Repellent Lotion, 4 ozHealth & Safety
Mosquitoes are common in the wet months, and picaridin lotion lasts in the heat.
- RAYMYLO 64 oz Insulated Water BottleWater Bottles & Hydration
A big insulated bottle keeps water cold through 34°C (93°F) afternoons.
- Crocs Classic ClogFootwear & Shoe Care
Clogs slip off fast at temple doors and handle wet streets in the monsoon.
- Dramamine Less Drowsy ChewablesHealth & Safety
The ferry from the mainland and trips to Ang Thong can be rough.
Clothing
- Light cotton or linen tops · 5Highs of 29–35°C all year
- Shorts · 3
- Pants or skirt covering knees · 1Temples like Wat Plai Laem and the Big Buddha
- Sarong or light scarf · 1Covers shoulders at temples
- Swimwear · 2
- Light rain jacket · 1Oct–Dec monsoon, up to 24 rain days
Footwear
- Quick-dry sandals · 1 pair
- Sneakers · 1 pairHike to Na Muang waterfall
- Water shoes · 1 pairRocky beaches
Gear
- Sun hat
- Sunglasses
Health and toiletries
- Reef-safe sunscreen
- After-sun lotion
Documents and money
- Passport
- Travel insurance
Tech
- Phone dry bag · 1
What shoes should you pack for Koh Samui?
Sandals and one pair of sneakers. Sandals handle beaches and temple steps, where you take shoes off anyway. Sneakers are worth packing for the hike to Na Muang waterfall and for wet, uneven paths. Water shoes help on rocky beaches.
What do people wear in Koh Samui?
Beachwear on the beach, covered up elsewhere. At temples such as Wat Plai Laem and the Big Buddha, cover shoulders and knees and take your shoes off. Walking through towns in swimwear or shirtless is frowned on. A light sarong or scarf in your bag solves most dress-code problems.
Is Koh Samui's rainy season different from Krabi's?
Yes. Samui is on the Gulf of Thailand side, wettest October–December. Krabi and Phuket on the Andaman side are wettest May–October. If you travel in the European summer, Samui is usually the drier choice; in November, the Andaman side usually wins.
What plugs does Koh Samui use?
Thailand uses Type A, B, C and O sockets at 230V. Many sockets take US flat pins and European round pins, but not all, so bring a universal adapter. UK visitors need an adapter. Check that hair tools are dual voltage.
Tours and things to do in Koh Samui
Packed and ready? Browse guided tours, day trips and tickets for Koh Samui.
What should you leave at home for Koh Samui?
Leave jeans, heavy shoes and warm layers. Do not pack vapes or e-cigarettes: they are illegal in Thailand, and fines are steep. Skip clothes with Buddha images. Leave expensive jewelry at home for boat days and markets.
Packing for Koh Samui: questions people ask
What should I wear in Koh Samui in November?
Light clothes, a rain jacket and quick-dry sandals. November averages a 30°C (86°F) high, a 25°C (77°F) low and 24 rain days.
When is the rainy season in Koh Samui?
October to December. November is wettest, with 24 rain days on average.
What is the hottest month in Koh Samui?
June, with an average high of 35°C (95°F).
What should I wear to temples in Koh Samui?
Cover shoulders and knees and remove shoes before entering. A sarong over shorts works.
Do I need a plug adapter for Koh Samui?
Probably. Thailand mixes Type A, B, C and O sockets at 230V, so a universal adapter is safest.
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