September · Thailand weather
Thailand in September: Weather, What to Expect & Where to Go
September is Thailand's wettest month. Bangkok and the Andaman coast get the worst of it; even the Gulf starts to dampen by month-end. If you're not tied to school holidays, it's the cheapest month to visit — but plan around weather, not the other way around.
Best region
Gulf
Still the driest region — Samui's wet season hasn't fully started.
Avoid
Andaman
Phuket and Krabi see their wettest month of the year. Flooding is common in low-lying areas.
Wet-season peak
September is the wettest month nationwide. Flights and hotels are at their cheapest, but plan around rain — not the other way around.
September weather, region by region
Average temperatures and rainfall across Thailand's five climate regions in September. Tap the climate map on the homepage for an interactive month-by-month view.
| Region | Avg temp | Rainfall | Visit rating |
|---|---|---|---|
North Chiang Mai | 27°C | 220mm | Good |
Northeast Nakhon Ratchasima (Korat) | 28°C | 230mm | Good |
Central Bangkok | 29°C | 320mm | Mixed |
Andaman Phuket | 28°C | 400mm | Good |
Gulf Koh Samui | 28°C | 170mm | Great |
City spotlights
One city per region — what September actually feels like on the ground, and what to do or skip.
North
Chiang Mai
Wet, but mountain views between storms are stunning. Cheap, quiet, and atmospheric — bring waterproofs.
Year-round climate
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Northeast
Nakhon Ratchasima (Korat)
Heaviest rain of the year for Isaan. Khao Yai's waterfalls are at peak power but trails turn to mud — go with a guide or skip the long hikes.
Year-round climate
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Central
Bangkok
Highest monthly rainfall of the year. Flash flooding shuts roads regularly — skip if you want predictable sightseeing.
Year-round climate
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Andaman
Phuket
Wettest month of the year. Long-tail boats stay docked, dive operators are closed, beaches see rough surf.
Year-round climate
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Gulf
Koh Samui
Still relatively dry — your best beach option in September. Worth combining with the Phuket Vegetarian Festival as a day trip.
Year-round climate
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Events & festivals in September
Vegetarian Festival (Phuket)
Nine-day Taoist festival, dates shift annually but usually fall in late September or early October. Phuket Town is the centre — vegetarian food everywhere, plus street processions with body-piercing rituals.
Is September a good time to visit Thailand?
September is the cheapest, wettest month. Worth it for experienced travellers or culture-focused trips; not worth it for first-time visitors who want a guaranteed-sun beach holiday.
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Thailand in August
Gulf islands, cultural Bangkok
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Thailand in October
Andaman returning to form, end-of-Lent festivals
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