Compare Thai cities, side by side.

Thirty years of weather, twelve Thai stations

Every figure in this table is read from the station data sheets Thailand submitted to the World Meteorological Organization for the 1991–2020 standard normals period, archived by NOAA’s National Centers for Environmental Information as Accession 0253808. Each row carries its WMO station number so any number here can be checked against the same file. Rain days counts days with at least 1 mm of precipitation. Hottest is the highest monthly mean of the daily maximum and coolest the lowest monthly mean of the daily minimum — not record extremes, which are far wider.

Six of the twelve stations — Pattaya, Phuket, Ko Lanta, Ko Samui, Surat Thani and Udon Thani — returned no sunshine-duration series in the 1991–2020 submission. That column is left blank for them rather than filled from another source.

Three things fall out of the table that people rarely have straight before they arrive. Hua Hin is the driest place in the set, at 935.9 mm a year on 72.9 rain days — about 41% of Phuket’s rainfall on half the rain days, which is much of why it works as a year-round base for people who cannot face a monsoon. Pattaya is markedly drier than Rayong, 1,105.8 mm against 1,406.7 mm, despite sitting on the same stretch of Gulf coast. And Chiang Mai is not a wet city: at 1,139.2 mm it takes less rain over the year than Bangkok’s 1,702.2 mm, but it takes it in a narrower window — and its two darkest months, July and August at 115.3 and 110.8 hours of sunshine, are darker than any month Bangkok records.

If the weather is the deciding factor rather than one input among several, read the weather and seasons guide next, and flooding and monsoon season if you are looking at ground-floor property or a low-lying district.

The two coasts have opposite wet seasons

This is the most consequential thing on the page and the one most often got wrong, because “Thailand’s rainy season” is written about as though the country had one. It does not. The Andaman side takes the southwest monsoon and peaks in late summer; the Gulf side takes the northeast monsoon and peaks at the end of the year, once the Andaman has dried out. Here are the two monthly normals next to each other, same source and period as the table above.

Millimetres, 1991–2020 normals. Bold marks a month over 300 mm.

In September, Phuket’s wettest month, the normal is 350.4 mm; Ko Samui’s September normal is 117.5 mm, about a third of it. Two months later the position reverses: Ko Samui’s November normal of 444.6 mm is higher than any single month Phuket records, while Phuket is down to 178.2 mm. The practical consequence for anyone choosing a base rather than a holiday is that the two coasts are complementary, not interchangeable — and that a lease signed on the strength of a February viewing tells you very little about October. Island living in Thailand covers what that does to ferries, deliveries and rents; beaches and water safety covers what it does to the sea itself.

The dry season in the north is the trade-off

Thailand’s 24-hour ambient standard for PM2.5 is 37.5 micrograms per cubic metre. In its own 2025 haze-season briefing, the Pollution Control Department sets 2025 targets against 2024 performance and lists days over that standard by region: North 129, Northeast 113, Central 101, Bangkok and vicinity 97, West 84. The north leads the country, and by enough that it belongs in a decision about where to live rather than in a footnote.

Two things that briefing does not say, and which this page therefore does not claim: it gives no figure for Chiang Mai on its own, and it does not state whether the regional day counts are a maximum at one station or an average across a region’s stations. What the climate normals do show is why the season exists at all. Chiang Mai’s February normal is 9.6 mm and its March normal 20.4 mm — two months with almost no rain to clear the air — and its March mean relative humidity of 53.6% is the driest air of any station in the table. For the detail, and for what people actually do about it, see air quality in Thailand.

What this page does not know

• Krabi town and Ko Phangan have no station in Thailand’s WMO 1991–2020 submission. Ko Lanta is the nearest station in Krabi province and Ko Samui the nearest to Ko Phangan, but neither is that place and no figure is printed as though it were.
• Sunshine hours are missing for six stations, as marked in the table. They are left blank rather than substituted from a modelled dataset.
• Cost of living is a ranking, not a measurement on this site. The head-to-heads score it 1–5 relative to each other, consistent with each city guide’s own prose. No baht figure is attached to it here.
• No population figures appear on this page. Provincial registered-population totals were not confirmed against the Department of Provincial Administration’s own publication in this pass, so none are printed.
• Normals are averages, not forecasts. A 1991–2020 normal describes a thirty-year climate, not the year you will actually live through, and it says nothing about record extremes.

The next three questions

Choosing the city is the first of three decisions, and the other two constrain it more than people expect. The visa route you qualify for sets how long you can stay and whether you can work from here at all — start at Thailand visa routes. What you can own, as against what you can lease, is set by law rather than by the agent — the BAANLYY calculators and tools cover the foreign-ownership arithmetic. And the stock itself varies enormously by city: browse homes and condos, or read the building profiles if you want to know who built a tower and when before you view it. If you would rather find your people first, expat communities in Thailand maps where they already are.

Frequently asked questions