Bangkok in April

April is the hottest month of the year in Bangkok — and arguably the busiest. Average highs of 36 °C are routinely exceeded; afternoon temperatures of 39–41 °C in the sun are common, and humidity creeping back up makes it feel even hotter. Yet hotels, restaurants, and the airport are jammed: Songkran (13–15 April, often extended into a 5-day national holiday) is Thailand's biggest celebration, drawing millions of domestic travellers back to home villages and international visitors here to experience the world's largest water fight. If you want to come for Songkran, book by mid-February; if you want to avoid it, the first ten days and the last week of April are your windows.

Pure logistics during Songkran: BTS, MRT, malls, and tourist sites all stay open and air-conditioned. Streets in Silom, Khao San Road, RCA, and Sukhumvit Soi 11 are full of water-throwing crowds from morning until evening. Carry phones in waterproof pouches (10 THB from any 7-Eleven), don't ride motorbikes (drunk-driving spikes), and expect taxis and Grabs to surge 2-3×. Outside the festival itself, April is also peak honeymoon season for the islands: Phuket, Krabi, and Koh Samui all run at maximum occupancy, so you'll want flights and beach hotels booked at least six weeks ahead.