Coral Cove Beach, Ko Samui – Image courtesy of Fabio Achilli/Wiki Commons
Best time to visit Ko Samui
The best time to visit Ko Samui is during the dry season from mid-December to April, with February to April the driest months averaging 28°C (82°F).
Ko Samui Weather
Ko Samui is considered a year-round destination, but it’s probably best to avoid November – the wettest month of the year.
A short rainy season lasts from mid-September to mid-December and is characterised by hot, sunny days interspersed with occasional short bursts of heavy rainfall.
At other times, especially from April onwards, you can expect the occasional tropical rainfall, which typical lasts only 10 to 20 minutes. May is the hottest month in Ko Samui with an average temperature of 30°C (85°F)
October to January also brings strong winds that can make the east side of Ko Samui rough for swimming, while the island's west side is often buffeted by summer monsoon winds during July and August.
Seawater temperatures remaining fairly constant year round at 29°C.
Seasons
High season: Christmas and New Year, and from January through early July.
Low season: Mid-September to early-December
Ko Samui – Monthly Weather
| J | F | M | A | M | J | J | A | S | O | N | D | |
| Ave Temp (°C) | 27 | 27 | 28 | 28 | 29 | 29 | 29 | 29 | 28 | 28 | 27 | 26 |
| Ave High Temp (°C) | 29 | 30 | 31 | 32 | 33 | 32 | 32 | 32 | 32 | 31 | 30 | 29 |
| Ave Low Temp (°C) | 24 | 25 | 26 | 26 | 26 | 26 | 25 | 25 | 25 | 25 | 24 | 24 |
| Sunshine (Hrs daily) | 7 | 8 | 8 | 8 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 7 |
| Daylight (Hrs daily) | 12 | 12 | 12 | 12 | 13 | 13 | 13 | 12 | 12 | 12 | 12 | 12 |
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| Ave Humidity (%) | 85 | 85 | 85 | 80 | 80 | 80 | 80 | 80 | 80 | 85 | 85 | 85 |
| UV Index | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 10 |
| Days with some Rain | 7 | 5 | 5 | 5 | 9 | 9 | 9 | 10 | 11 | 16 | 15 | 9 |
| Ave Rainfall (mm) | 90 | 30 | 30 | 80 | 160 | 100 | 120 | 100 | 130 | 290 | 430 | 150 |
| Sea Temp (°C) | 28 | 28 | 29 | 30 | 30 | 30 | 29 | 29 | 29 | 29 | 29 | 28 |
| (Ko Samui, Thailand) | J | F | M | A | M | J | J | A | S | O | N | D |
Ko Samui – Monthly Review
| › January | › February | › March | › April |
| › May | › June | › July | › August |
| › September | › October | › November | › December |
Note: Meteorological data is sourced from the United States National Oceanic and Atmospheric Administration (NOAA) and the World Meteorological Organization (WMO), with additional historical climate data sourced from the Thai Meteorological Department.
Latest update: Best time to visit Ko Samui: 18 November, 2018
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