Chiang Mai weather in September
September in Chiang Mai: sweltering, soaked, with very humid — a fair time to visit.
#11 of 12 months in Chiang Mai · #553 of 604 destinations to visit in September · comfort 54/100 (tier D)
Updated June 2026 · climate normals from ERA5 reanalysis
Chiang Mai climate normals — September
| Daytime high | 30°C / 85°F | 🔥 sweltering |
|---|---|---|
| Nighttime low | 23°C / 74°F | |
| Feels like (high) | 36°C / 97°F | |
| Rainfall | 237 mm / 9.3 in | ⛈ soaked |
| Rainy days | 23 days | |
| Humidity | 87% | 💦 very humid |
| Dew point | 24°C / 74°F | |
| Sunshine | 8.7 h/day | |
| Daylight | 12.2 h | |
| Wind | 7 km/h / 4 mph | |
| Air quality (US AQI) | 53 | 🙂 moderate |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Chiang Mai in September — FAQ
- Is September a good time to visit Chiang Mai?
- September in Chiang Mai: sweltering, soaked, with very humid — a fair time to visit. It ranks #11 of 12 months for Chiang Mai on SeasonMap's comfort score (54/100).
- What is the weather like in Chiang Mai in September?
- In September, Chiang Mai averages a daily high of 29.7°C and a low of 23.3°C, with about 236.8 mm of rain over roughly 23 rainy days.
- What is the air quality in Chiang Mai in September?
- Chiang Mai has a mean US Air Quality Index of about 53 in September.