Climate averages 1991–2020
Chiang Mai weather
in September.
A hot, very wet month: the 7th warmest and the 11th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a hot month in Chiang Mai: daytime highs average 29.3°C and nights cool to about 22.9°C. By daytime temperature it is the 7th warmest of the 12 months.
Expect about 227 mm of rain on roughly 23 days, which makes September a very wet month (the 11th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 16 min on an average September day.
The nearest other city in this atlas is Lampang (77 km away). In September its highs average 29.1°C, about as warm as Chiang Mai, with 256 mm of rain.
Among the 46 cities listed in Thailand, Chiang Mai ranks 42nd of 46 for the warmest September highs and 11th of 46 for the driest September (rainfall, lowest first). The mean September high of those 46 cities is 30.3°C; Chiang Mai is 1.0°C cooler than that mean.
From September to October, average highs fall by 0.4°C to 28.9°C, and monthly rainfall falls from 227 mm to 114 mm.
The annual picture
September in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Chiang Mai climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 28.1°C16.2°C | 16.2°C | 6.7 | 1.3 | 11.111 h |
| February | 31.3°C18.4°C | 18.4°C | 3.3 | 0.7 | 11.512 h |
| March | 34.3°C21.7°C | 21.7°C | 12 | 2.1 | 12.012 h |
| April | 35.8°C24.5°C | 24.5°C | 26 | 4.3 | 12.613 h |
| May | 33.1°C24.6°C | 24.6°C | 99 | 13.1 | 13.013 h |
| June | 30.9°C24.1°C | 24.1°C | 120 | 18.3 | 13.213 h |
| July | 29.9°C23.8°C | 23.8°C | 175 | 21.9 | 13.113 h |
| August | 29.1°C23.4°C | 23.4°C | 236 | 25.0 | 12.813 h |
| September, selected | 29.3°C22.9°C | 22.9°C | 227 | 23.4 | 12.312 h |
| October | 28.9°C21.5°C | 21.5°C | 114 | 15.7 | 11.712 h |
| November | 28.3°C18.8°C | 18.8°C | 21 | 4.0 | 11.311 h |
| December | 27.1°C16.0°C | 16.0°C | 9.1 | 1.2 | 11.011 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Lampang in SeptemberThailand · 77 kmHigh 29.1°C · Low 23.3°C · 256 mm rain
- Chiang Rai in SeptemberThailand · 153 kmHigh 29.0°C · Low 22.9°C · 295 mm rain
- Nyaunglebin in SeptemberMyanmar · 256 kmHigh 29.1°C · Low 23.7°C · 316 mm rain
- Taungoo in SeptemberMyanmar · 269 kmHigh 28.8°C · Low 23.5°C · 247 mm rain
- Thaton in SeptemberMyanmar · 269 kmHigh 28.8°C · Low 24.1°C · 537 mm rain
- Mawlamyine in SeptemberMyanmar · 293 kmHigh 28.4°C · Low 24.1°C · 469 mm rain
- Yawnghwe in SeptemberMyanmar · 299 kmHigh 26.6°C · Low 20.1°C · 159 mm rain
- Taunggyi in SeptemberMyanmar · 301 kmHigh 23.5°C · Low 17.0°C · 159 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Chiang Mai) is explained once on the Chiang Mai year overview and on the Sources, method and limits page.