| Month | Mean, °C | Mean max, °C | Mean min, °C | Lowest recorded, °C | Rain, mm | Rain days | Humidity, % |
|---|---|---|---|---|---|---|---|
| January | 22.0 | 30.0 | 15.7 | 8.7 | 11.3 | 1.3 | 69 |
| February | 24.2 | 32.9 | 16.8 | 9.4 | 9.6 | 0.9 | 58 |
| March | 27.3 | 35.4 | 20.1 | 13.8 | 20.4 | 2.8 | 54 |
| April | 29.5 | 36.7 | 23.4 | 18.6 | 54.3 | 6.8 | 57 |
| May | 28.6 | 34.7 | 24.2 | 18.3 | 167.5 | 14.8 | 71 |
| June | 28.0 | 33.2 | 24.5 | 21.2 | 118.2 | 16.3 | 76 |
| July | 27.4 | 32.1 | 24.3 | 21.1 | 148.6 | 18.8 | 79 |
| August | 26.9 | 31.6 | 24.0 | 21.7 | 223.3 | 20.9 | 82 |
| September | 26.9 | 32.0 | 23.7 | 19.5 | 207.2 | 18.1 | 82 |
| October | 26.4 | 31.7 | 22.6 | 14.0 | 123.8 | 11.8 | 79 |
| November | 24.6 | 30.8 | 19.9 | 10.6 | 40.9 | 4.2 | 75 |
| December | 22.2 | 29.2 | 16.9 | 3.8 | 14.1 | 1.8 | 73 |
| Year | 26.2 | 32.5 | 21.3 | 3.8 | 1,139.2 | 118.5 | 71 |
The table above is a climate normal: averages over 30 years, not a forecast for any given year. A single year can be drier or wetter, warmer or cooler. For planning a trip or a move, the normal is more useful than last year’s weather: it shows what to expect in a typical month.
What the numbers show
Cool nights from November to February. The average low is 19.9 °C in November, 16.9 °C in December, 15.7 °C in January and 16.8 °C in February. Days stay warm, 29.2-32.9 °C, so the gap between day and night in January and February is 14-16 degrees (our calculation from the table). The lowest temperatures recorded at the station in 1991-2020 were 3.8 °C in December and 8.7 °C in January.
March and April are the hot season. Highs average 35.4 °C in March and 36.7 °C in April. The record for 1991-2020, 42.5 °C, was set in May, just before the rains.
The rains run from May to October. Each month gets 118.2-223.3 mm, with the most in August and September. From December to March it is very dry: 9.6-20.4 mm a month and 0.9-2.8 rain days. TMD counts a rain day whenever at least 0.1 mm falls, so short showers count too.
The dry months are sunny and dry-aired. Humidity falls to 54% in March. The station gets 2,436.3 hours of sunshine a year, most in March (267.9 hours) and least in August (110.8).
Chiang Mai weather by season
Our grouping of the monthly TMD figures in the table above (Chiang Mai station, 1991-2020). Haze days are explained below.
| Period | Months | Mean min, °C | Mean max, °C | Rain a month, mm | Rain days a month | Days with haze a month |
|---|---|---|---|---|---|---|
| Cool and dry | November-February | 15.7-19.9 | 29.2-32.9 | 9.6-40.9 | 0.9-4.2 | 7.8-22.1 |
| Hot | March-April | 20.1-23.4 | 35.4-36.7 | 20.4-54.3 | 2.8-6.8 | 17.1-26.8 |
| Rainy | May-October | 22.6-24.5 | 31.6-34.7 | 118.2-223.3 | 11.8-20.9 | 0.0-6.7 |
The same months across the country: Thailand in November and Thailand in December.
Haze days in the TMD report
The report lists the number of days a month on which the station recorded haze. At Chiang Mai there are 115.7 such days a year, almost all from December to April, with a peak of 26.8 in March. Average visibility at the station is also lowest in March, 7.4 km, against 11.6 km in June.
These are weather observations, not measurements of PM2.5 or an air quality index: the TMD report has no air quality data. How to read PM2.5 and where to check it before the trip is in Chiang Mai smoke season.
Chiang Mai and Chiang Rai compared
Chiang Rai is about 162 km north-east of Chiang Mai in a straight line (our calculation from the station coordinates). Its station is higher and its nights are cooler.
| Figure | Chiang Mai (48 327) | Chiang Rai (48 303) |
|---|---|---|
| Station elevation | 305 m | 388 m |
| Mean annual temperature | 26.2 °C | 24.8 °C |
| Average low in January | 15.7 °C | 13.8 °C |
| Lowest recorded, 1991-2020 | 3.8 °C, December | 1.5 °C, December |
| Annual rainfall | 1,139.2 mm | 1,723.5 mm |
| Rain days a year | 118.5 | 136.0 |
| Days with haze a year | 115.7 | 82.2 |
| Days with fog a year | 3.8 | 28.4 |
| Sunshine a year | 2,436.3 hours | 2,412.6 hours |
Month by month for the north: Chiang Rai weather. Buses and minivans between the two: Chiang Mai to Chiang Rai and Pai.
Today’s forecast and warnings from TMD
The normals show a typical month, not the coming week. For the next seven days use the TMD 7-day forecast, which is given by region. Heavy rain and storm warnings are on the TMD warnings page.
Method and limits
- Source: Thai Meteorological Department report Climatological Data of Thailand for 30 Year Period (1991-2020), 2023 edition, printed page 5 (Chiang Mai, WMO 48 327); Chiang Rai on page 3. The report is published on a TMD subdomain
- Station: 18°46’ N, 98°58’ E, 305 m above sea level
- Period: 30 years, 1991-2020, the latest 30-year period for which TMD has published normals
- How we compiled it: figures copied from the report without recalculation. We checked monthly rainfall, rain days, haze days and sunshine against the annual values and found no discrepancies
- Lowest recorded: the report’s extreme minimum for each month over 1991-2020, a single coldest reading, not a typical night
- Rain day: at least 0.1 mm in 24 hours, counted from 07:00 to 07:00
- What is missing: air quality and PM2.5. The haze days in the report are weather observations at the station, and we do not treat them as a smoke measurement
- Next update: when TMD publishes new normals or at our April 2027 review
Where to stay, getting around and a three-day plan: Chiang Mai travel guide. Getting there: Bangkok to Chiang Mai.
FAQ
What is the best month for weather in Chiang Mai?
For dry, mild weather, November to February: 9.6-40.9 mm of rain a month, highs of 29.2-32.9 °C and nights of 15.7-19.9 °C. December and January are the coolest. From February the station records more and more days with haze, 22.1 in February and 26.8 in March, so check air quality before a late-season trip.
Is it cold in Chiang Mai in winter?
Days stay warm, nights do not. In January the average low is 15.7 °C against a high of 30.0 °C. The lowest temperature recorded at the station over 1991-2020 was 3.8 °C, in December. A warm layer for evenings and early mornings is useful from December to February.
When is the rainy season in Chiang Mai?
On the 1991-2020 normals, May to October: 118.2-223.3 mm a month and 11.8-20.9 rain days. The wettest months are August and September (223.3 and 207.2 mm). In November rainfall drops to 40.9 mm.
When is the dry season in Chiang Mai?
November to April. From December to March each month gets 9.6-20.4 mm and fewer than 3 rain days on average; February is the driest with 9.6 mm. November (40.9 mm) and April (54.3 mm) are the edges of the dry season.
What is the hottest month in Chiang Mai?
April: a mean of 29.5 °C and an average high of 36.7 °C. March is close behind with highs of 35.4 °C. The highest temperature recorded at the station over 1991-2020, 42.5 °C, was in May.
What is the coolest month in Chiang Mai?
January: a mean of 22.0 °C and an average low of 15.7 °C. December is almost the same, 22.2 °C, and has the lowest temperature on record at the station for 1991-2020: 3.8 °C.
What is the weather like in Chiang Mai in November?
November is when the rains end and the cool season begins: 40.9 mm and 4.2 rain days on average, a third of October's 123.8 mm. Highs are 30.8 °C, lows 19.9 °C, humidity 75%. TMD recorded haze on 7.8 days in November on average.
What is the weather like in Chiang Mai in December?
December is dry and cool: 14.1 mm and 1.8 rain days, a mean of 22.2 °C, highs of 29.2 °C, the lowest of the year, and lows of 16.9 °C. It has 238.0 hours of sunshine on average.
When is the haze season in Chiang Mai?
In the TMD normals, days with haze cluster from December to April: 13.5 in December, 18.7 in January, 22.1 in February, 26.8 in March and 17.1 in April, against 0.0-1.5 from May to September. This is a weather observation, not a PM2.5 measurement. How to check particle levels is in our page on the Chiang Mai smoke season.
Sources
Found an error or outdated fact? Tell the editors, we will fix it and update the check date.