Thailand sits in the tropics, so warmth and humidity are normal almost everywhere. What surprises many visitors is how differently the year feels between Bangkok, the northern mountains, and the two coasts (Andaman vs Gulf). We group the year into three seasons that Thais actually talk about—not four European-style seasons.
For a quick country snapshot, see our Thailand overview — geography and climate and regions guide.
The three seasons Thais use
Hot season (roughly March–May)
Temperatures climb nationwide. In the central plains and Bangkok, afternoon highs often reach 35–40°C. Songkran (Thai New Year, mid-April) falls in this period—wonderful for festivals, brutal for midday sightseeing without shade. Drink water constantly; air-conditioned malls and BTS/MRT stations are your friends.
Cool / dry season (roughly November–February)
This is what we call “หน้าหนาว” (cool season), though “cool” is relative—Bangkok evenings might be 22–28°C, while Chiang Mai mornings can dip toward 10–15°C on mountain peaks. Rain is less frequent; skies are clearer. It is peak tourist season: book flights and popular hotels early, especially late December through January.
Rainy / monsoon season (roughly June–October)
Southwest monsoon brings heavier showers, often in afternoon bursts rather than all-day drizzle (though multi-day wet spells happen). Central and northern areas green up beautifully. Prices and crowds often drop outside school holidays. Carry a light rain jacket; street flooding in Bangkok can appear quickly after downpours—check routes before you commit to a long taxi ride.
Regional differences
- Central Thailand (Bangkok, Ayutthaya): Three-season pattern is clearest. Hottest pre-monsoon stretch is April–May. See Bangkok destination guide.
- North (Chiang Mai, Chiang Rai, Pai): Cool season is the sweet spot for temples and Doi Inthanon; burn season (agricultural haze, often February–April) can affect air quality—check local PM2.5 reports if you have respiratory issues. Chiang Mai.
- Northeast (Isan): Hot and dry for long stretches; rainy season storms can be intense but brief. Great for culture and food, less for beach plans.
- Andaman coast (Phuket, Krabi, Trang): Best sea conditions for many islands is often November–April; monsoon on this side is typically May–October with choppier seas and some park closures. Phuket.
- Gulf coast (Samui, Phangan, Tao, eastern islands): Rain pattern is offset from the Andaman—many travelers aim for February–June on this side, while the Andaman may already be excellent. Do not assume “south = same weather.”
Our month-by-month guide breaks down events and travel tips for each month.
Best time by activity
| Activity | When we’d aim to go | Notes |
|---|---|---|
| Temples & city walking (Bangkok) | November–February | Mornings are comfortable; avoid midday in April. |
| Northern mountains & trekking | November–February | Pack a light jacket for Chiang Mai nights. |
| Andaman beaches & diving | December–April | Confirm national park boat schedules in shoulder months. |
| Gulf islands (Samui area) | Late January–June (varies by year) | Cross-check TMD marine forecasts. |
| Festivals (Songkran, Loy Krathong) | April; November (lunar calendar) | See holidays & festivals and travel during public holidays. |
| Lower prices & fewer crowds | May–June, September–October (avoid long weekends) | Rain likely; flexibility helps. |
FAQ
Is rainy season a bad time to visit?
Not necessarily. You may get sunny mornings and dramatic afternoon storms. Islands have more variable boat service. If your trip is flexible and you like lush scenery and deals, rainy season can work well.
Does Thailand have a “winter”?
We call November–February the cool season. Only high northern elevations feel truly cold to Europeans; Bangkok rarely needs more than a light layer at night.
Where is the official forecast?
Use TMD for national and regional forecasts. Tourism planning context: Tourism Authority of Thailand .
Sources & references
Content reviewed against the sources below on 24 May 2026. Rules, fees, and phone numbers can change—confirm critical details with official agencies before you travel.