| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 21.3° | — | 34.8mm | 3.8 | 92 |
| February | 24.2° | — | 24.2mm | 3 | 94 |
| March | 27.2° | — | 41.3mm | 5.7 | 88 |
| April | 30.1° | 18.3° | 107mm | 10 | 68 |
| May | 30.4° | — | 150.5mm | 13.4 | 60 |
| June | 30.3° | — | 193.9mm | 15.3 | 57 |
| July | 30° | — | 242.9mm | 18.7 | 58 |
| August | 30.1° | — | 263.4mm | 18.2 | 58 |
| September | 29.6° | — | 108.5mm | 11.3 | 67 |
| October | 27.8° | — | 45.2mm | 5 | 87 |
| November | 25.2° | — | 23.4mm | 3.3 | 93 |
| December | 21.7° | — | 23.7mm | 3.2 | 94 |
January in Sơn La averages a daily high of 21.3°C. Expect roughly 3.8 wet days totalling 34.8mm. Comfortable conditions for being outdoors all day.
February in Sơn La averages a daily high of 24.2°C. Expect roughly 3 wet days totalling 24.2mm. Comfortable conditions for being outdoors all day.
March in Sơn La averages a daily high of 27.2°C. Expect roughly 5.7 wet days totalling 41.3mm. Comfortable conditions for being outdoors all day.
April in Sơn La averages a daily high of 30.1°C with nights around 18.3°C. Expect roughly 10 wet days totalling 107mm. Generally workable, with some weather to plan around.
May in Sơn La averages a daily high of 30.4°C. Expect roughly 13.4 wet days totalling 150.5mm. Generally workable, with some weather to plan around.
June in Sơn La averages a daily high of 30.3°C. Expect roughly 15.3 wet days totalling 193.9mm. Generally workable, with some weather to plan around.
July in Sơn La averages a daily high of 30°C. Expect roughly 18.7 wet days totalling 242.9mm. Generally workable, with some weather to plan around.
August in Sơn La averages a daily high of 30.1°C. Expect roughly 18.2 wet days totalling 263.4mm. Generally workable, with some weather to plan around.
September in Sơn La averages a daily high of 29.6°C. Expect roughly 11.3 wet days totalling 108.5mm. Generally workable, with some weather to plan around.
October in Sơn La averages a daily high of 27.8°C. Expect roughly 5 wet days totalling 45.2mm. Comfortable conditions for being outdoors all day.
November in Sơn La averages a daily high of 25.2°C. Expect roughly 3.3 wet days totalling 23.4mm. Comfortable conditions for being outdoors all day.
December in Sơn La averages a daily high of 21.7°C. Expect roughly 3.2 wet days totalling 23.7mm. Comfortable conditions for being outdoors all day.
Each month scores out of 100. It starts at 100 and loses points for daytime highs outside a 20–27°C band, for wet days, and for nights below 2°C. Nothing else is weighted in — no crowd data, no prices, no opinion. Sơn La peaks at 94.
Based on 30 years of records, October–March scores highest for comfort in Sơn La, balancing daytime temperature against rainfall.
May is the warmest, averaging a daily high of 30.4°C.
August is the wettest, averaging 263.4mm of rain across roughly 18.2 wet days.
January is the coolest month, with average daily highs around 21.3°C.