Chiang Mai and the hills — cooler than the south, but with a burning season the brochures omit. Daytime highs in northern Thailand run from about 26 °C in December to 33 °C in April, an annual range of roughly 7 °C.
Measured against a city trip, the conditions hold up November to January. December is the most consistent single month: highs near 26 °C, nights around 15 °C, and roughly 17 mm of rain across the month.
The binding constraint here is temperature and rainfall — that is what rules months out, not any composite judgement. Rainfall is sharply seasonal: August averages 302 mm against 6 mm in February, so the wet season is the real planning constraint rather than heat or cold. February is the weakest month on these criteria.
Month by month
| Month | High °C | Low °C | Precip mm | Wet days |
|---|---|---|---|---|
| January | 26 | 14 | 22 | 2.6 |
| February | 29 | 16 | 6 | 2.0 |
| March | 32 | 19 | 22 | 3.9 |
| April | 33 | 22 | 94 | 9.6 |
| May | 31 | 22 | 182 | 21.4 |
| June | 29 | 22 | 221 | 25.7 |
| July | 28 | 22 | 269 | 27.9 |
| August | 28 | 22 | 302 | 28.7 |
| September | 28 | 21 | 253 | 26.0 |
| October | 27 | 20 | 140 | 18.2 |
| November | 27 | 18 | 37 | 7.0 |
| December | 26 | 15 | 17 | 3.3 |
Ticked rows are months where every hard requirement for a city trip is met across at least half the month.
Open Northern Thailand on the map →Nearby regions
Figures are 30-year climatology sampled at Chiang Mai, Chiang Rai, Pai, Lampang and Doi Inthanon, averaged across those locations, from ERA5-Land reanalysis fitted with a harmonic seasonal cycle and a trend term, evaluated for 2026. Sampling named towns rather than averaging the whole region avoids blending valley and mountain conditions into a figure true of neither. Cells are about 0.08° wide, from ERA5-Land's 0.1° grid, which is itself driven by a 0.25° (~28 km) atmospheric reanalysis — so individual valleys, sheltered bays and single summits are not resolved. In steep terrain read these as conditions for the wider area rather than for one village. They describe typical conditions, not a forecast. Read how the climatology is built.