When to Go
In high season, between November and February, temperatures in Bangkok can drop into the 70s, the humidity becomes far less oppressive, and the city feels downright pleasant. Within that season, the absolute best time to visit is between mid-December and mid-January.
Low season is generally between July and October, when the city is subject to monsoon rains. However, it doesn’t rain all day or even every day; if you don’t mind a few downpours and occasional street flooding, you’ll pay significantly less for accommodations during this time, and most sights will be far less crowded.
The hot season (Mar.-May) means higher temperatures, lots of humidity, and occasional storms. There’s a reason for the expression “Bangkok blanket.” Year-round you should make sure your accommodations have air-conditioning, but if you’re here during the hot season, it will be unbearable without it.
In mid-April the whole country celebrates Songkran, or Buddhist New Year, and while raucous water fights that last for days may seem totally out of place in a city as sophisticated as Bangkok, at least the dousing has the effect of cooling everyone down a bit. Though there are other significant holidays throughout the year, this is the only time some restaurants and small shops will close.
© Suzanne Nam from Moon Bangkok, 5th Edition