The best time to visit Northern Thailand (Chiang Mai) is Nov–Feb. It is the only stretch of the year — 4 months — rated go on both daytime heat and rainfall.
Cool dry Nov–Feb; burning season Mar–Apr
| Month | High °C | High °F | Rainy days | Verdict |
|---|---|---|---|---|
| January | 26.3 | 79 | 6% | Go |
| February | 29.7 | 85 | 4% | Go |
| March | 33.1 | 92 | 13% | Too hot |
| April | 34.3 | 94 | 36% | Too hot |
| May | 31.5 | 89 | 71% | Too wet |
| June | 30.0 | 86 | 76% | Too wet |
| July | 29.0 | 84 | 83% | Too wet |
| August | 27.9 | 82 | 87% | Too wet |
| September | 27.5 | 82 | 79% | Too wet |
| October | 26.7 | 80 | 54% | Fair |
| November | 25.7 | 78 | 17% | Go |
| December | 24.7 | 76 | 7% | Go |
Verdict combines mean daytime high with rainy-day frequency. “Rainy days” is the share of days in the month with at least 1 mm of rain.
February is the driest month, with rain on 4% of days and daytime highs near 29.7°C (85°F). August is the wettest, at 87%. The warmest month is April at 34.3°C (94°F); the coolest is December at 24.7°C (76°F). The record rules out too hot in Mar–Apr; too wet in May–Sep.