Weather in Koh Samui in April

How April compares

April is the 2nd warmest month of the year in Koh Samui and ranks 14th of 134 destinations we compare for April - see where else is hot in April. Within Thailand it is 5th of 6 (Thailand in April). Against London's average high of 13.5°C in April, Koh Samui is 16.5°C warmer by day and 22.2°C warmer at night.

Daytime and night-time in April

The typical April day in Koh Samui peaks at 30.0°C, but that is an average: the warmest 10% of days reach 31.4°C or more. About 100% of days top 25°C and 1 in 2 pass 30°C. Nights average 27.3°C; one night in ten drops to 25.8°C or lower, so pack a layer for evenings. Between 1991 and 2020 the hottest April day here reached 34.2°C (2019-04-17) and the coldest night 23.6°C (2017-04-05).

Rain in April

Wet (more than 8 rainy days): about 12 days with 1 mm or more, 96 mm in total. Year to year it varies a lot - the wettest April was 2013 with 328 mm, the driest 2016 with 2 mm. Humidity averages 77%, which makes the heat feel heavier than the thermometer suggests.

Sea temperature in April

The sea averages 30.3°C - warm enough to swim (22°c+). Depending on the year it ranges from 29.7°C to 30.7°C. For the warmest sea here, come in May (30.5°C).

Sunshine and daylight

Around 5.2 hours of sunshine a day (estimated from cloud cover), 12.2 hours of daylight: the sun rises about 06:10 and sets about 18:30 local time in mid-April. Average cloud cover is 57%.

Is April a good time to visit Koh Samui?

It is a reasonable choice: hot days but expect showers. The best months for Koh Samui on our scoring are February, March, January; months averaging 25°C or more: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec.

Expect heat that lasts into the evening

April is among Koh Samui's hottest months, so plan around the heat rather than treating it as occasional. Compared with London's April daytime high of 13.5°C, the island is 16.5°C warmer on average. Humidity of 77% adds to the discomfort, particularly if you want to spend much of the day walking around. Loose, light clothing, regular drinks and somewhere shaded to pause will be useful. Keep more demanding plans away from midday, and choose accommodation where you can cool down comfortably. Evenings are still warm: the average night low gives little reason to pack heavy layers for time outdoors.

Allow for rain without writing off the month

April is a wet choice, with about 12 rainy days, so a completely dry holiday is not a sensible expectation. That does not mean those days are washouts, but the figures do not tell you when rain will arrive or how long it will last. Keep outdoor plans flexible and carry lightweight rain protection rather than relying on a fixed daily routine. Sunshine averages about 5.2 hours within 12.2 hours of daylight, so daylight should not be mistaken for uninterrupted sun. This month suits travellers happy to adjust their plans; it is less appealing if guaranteed dry weather is central to the trip.