Thailand · 9.51°N 100.01°E · 30-year monthly averages, judged against the Tropical preset (highs 28–38 °C82–100 °F, any rain except monsoon)
The best time to visit Koh Samui is January to September, with highs of 29–33 °C84–91 °F and nights of 23–25 °C73–77 °F, and rainfall of 48–128 mm1.9–5.0 in a month.
The monsoon season is October to December, with 184–408 mm7.2–16 in a month and a peak in November (408 mm16 in). April is the hottest month (highs of 33 °C91 °F) and January the coldest (29 °C84 °F).
The figures are 30-year monthly averages (WorldClim 2.1 monthly normals 1970–2000) for the 0.25° grid cell at 9.51, 100.01. This is a climate guide, not a forecast.
Pick the weather you like. Every month is then judged against it: temperature above the month names, rain below.
Good time to go for a Tropical holiday: January to September.
Open Koh Samui on the interactive map ↗ the same verdicts for any place on Earth, in any month
Reading the chart. Gold means good: the month fits what you picked. Any other colour shows the reason it does not. The temperature bar can be too cold or too hot; the rain bar can be too dry, too rainy or monsoon. A faded gold bar means that half fits but the other half does not. A gold month name means both halves fit.
What the verdicts mean. Temperature is the month's average daily high (the afternoon), judged against the preset's band (highs 28–38 °C82–100 °F for Tropical). Rain is judged by each month's class within Koh Samui's own year, not by raw millimetres: dry under 60 mm2.4 in, showers 60–100 mm2.4–3.9 in, rainy from 100 mm3.9 in and at least 35 % of the wettest month. Too rainy is a rainy-season month that the preset does not allow. Monsoon is the heaviest kind of rainy season: 180 mm7.1 in or more (120 mm4.7 in near the yearly peak) in a climate where the wettest month has at least three times the rain of the driest. Every monsoon month is also a rainy-season month; the label says which kind. Full rules on the method page.
| Month | Rain | High | Low | Season | Tropical verdict |
|---|---|---|---|---|---|
| January | 803.1 | 2984 | 2373 | showers | good |
| February | 481.9 | 3086 | 2474 | dry | good |
| March | 722.8 | 3188 | 2576 | showers | good |
| April | 722.8 | 3391 | 2577 | showers | good |
| May | 1285.0 | 3391 | 2577 | showers | good |
| June | 883.5 | 3289 | 2577 | showers | good |
| July | 883.5 | 3289 | 2576 | showers | good |
| August | 1044.1 | 3289 | 2576 | showers | good |
| September | 1285.0 | 3188 | 2475 | showers | good |
| October | 26410 | 3086 | 2474 | monsoon | monsoon |
| November | 40816 | 2984 | 2474 | monsoon | monsoon |
| December | 1847.2 | 2984 | 2373 | monsoon | monsoon |
| Looking for | Rule | Months that fit |
|---|---|---|
| Warm | highs 19–28 °C66–82 °F, dry or showers | |
| Tropical | highs 28–38 °C82–100 °F, any rain except monsoon | January to September |
| Beach | highs 28–38 °C82–100 °F, dry or showers | January to September |
| Cool | highs 3–19 °C37–66 °F, any rain except monsoon | |
| Snow | highs below 3 °C37 °F, any rain |
Yes. The monsoon season is October to December, with 184–408 mm7.2–16 in a month and a peak in November (408 mm16 in). Outside the rainy season, February is dry.
April is the hottest month (highs of 33 °C91 °F) and January the coldest (29 °C84 °F). Annual rainfall is about 1,664 mm66 in.
The nearest destinations that fit the Tropical preset in the months when Koh Samui does not:
The interactive map colours the whole world by how well it fits the weather you like, in any month, and shows this chart for any place you tap.