Bangkok is warm year-round, but the seasons change the experience.
Cool, dry season (Nov–Feb) — best
The most comfortable months: warm days, lower humidity, little rain. Peak season, so book ahead.
Hot season (Mar–May)
Very hot and humid — pace yourself, use the air-conditioned malls and BTS, and stay hydrated.
Wet season (Jun–Oct)
Afternoon downpours rather than all-day rain, with fewer crowds and lower prices. Songkran (mid-April) is the famous water festival.
See also: the full Bangkok travel guide.