April is the hottest month, with Songkran on 13–15 April. Expect 35–38°C and high humidity on the coast, plus three days when the whole country stops for water fights. Beach prices are the lowest of the dry season until the festival.
The short version
- The hottest month — 35–38°C, and humid.
- Songkran, 13–15 April, shuts down transport and shops nationwide.
- Book Songkran accommodation two to three months ahead.
- The Andaman has calm seas and good visibility; the Gulf is starting to build.
Weather
36–38°C in Bangkok and Chiang Mai before Songkran. The Andaman is calm and swimmable; the Gulf is hot but fine. It is not a month for temple-hopping at midday.
Songkran
13–15 April is Thai New Year: three days of water fights, temple rituals and family reunions. Chiang Mai goes on for four or five days. Book hotels months ahead and expect transport to crawl.
How to plan around it
Go to the beach before or after Songkran rather than during it, and do your sightseeing at 7am. The week after Songkran is quiet and cheap — a good window if you do not need the festival.
Where to go in April
April is the Andaman's last good month before the monsoon and the best month for calm water. Phuket, Krabi and Koh Lanta are all at their hottest and their clearest, and the sea temperature is around 30°C, which is almost too warm to be refreshing.
Songkran changes the shape of the month. The first ten days are normal; the 13th to 15th are a nationwide water fight with disrupted transport; after the 17th the country returns to normal but prices stay low until May. If you want a beach holiday without the festival, travel in the first week.
The Gulf is the alternative for anyone who does not want the heat. Samui in April is 33°C rather than 38°C and the crossings are still calm, which makes it the more comfortable choice if you are travelling with children or older relatives.
