Chiang Rai weather by month
Chiang Rai runs from about 21°C in January to 28°C in April, with August the wettest month at 484 mm.
warmest month
April
28°C
coolest month
January
21°C
wettest month
August
484 mm
worst air month
April
67 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 21°C | 48 mm | 321 h | 19 |
| February | 23°C | 5 mm | 310 h | 26 |
| March | 25°C | 8 mm | 328 h | 47 |
| April | 28°C | 25 mm | 328 h | 67 |
| May | 27°C | 295 mm | 322 h | 18 |
| June | 26°C | 272 mm | 262 h | 12 |
| July | 26°C | 319 mm | 284 h | 11 |
| August | 25°C | 484 mm | 195 h | 10 |
| September | 26°C | 358 mm | 246 h | 7 |
| October | 25°C | 253 mm | 313 h | 9 |
| November | 23°C | 105 mm | 286 h | 10 |
| December | 22°C | 17 mm | 315 h | 15 |
About 3,510 hours of sun a year. Roughly 195 rainy days a year.
These are long-run climate normals, not a forecast. A given year can sit well outside them. PM2.5 is a global model: near the coast it counts sea salt as fine particulate and reads high against ground stations, sometimes by a factor of two. Use the shape of the year, not the absolute number.
where these numbers come from
- · Temperature, rainfall and sunshine: ECMWF ERA5 reanalysis climate normals via Open-Meteo (CC BY 4.0), fetched once and stored.
- · PM2.5: Copernicus CAMS reanalysis, monthly means. Modelled, not station readings; near coasts CAMS counts sea salt as PM2.5 and reads high.
Last reviewed 2026-05-23. Full method, licences and the list of sources we rejected are on the methodology page.