April in Ko Samui averages a daily high of 31.9°C with nights around 25.9°C. Expect roughly 4.4 wet days totalling 30.1mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Ko Samui is January–April.
Based on KO SAMUI, TH (14.7km), 1995–2024. 26 years of April data.