Chiang Mai Weather, Season by Season

Why the weather usually decides it

This is written for men in their 60s and 70s weighing up a winter, or a retirement, somewhere warmer than home. I have lived in Northern Thailand for more than ten years, and for most of the older Western men I know here, the climate was the main reason they came.

Chiang Mai sits in the mountains of the north, away from the humidity of the beach resorts in the south. It is not comfortable all year. There are three distinct seasons and one of them is hard work. The notes below are written from Baanpong Lodge, about 30 km east of the city in the San Kamphaeng / Mae On countryside.

Cool and dry: November to February

Daytime highs of 28–30°C (82–86°F) in November, easing to 27–29°C (81–84°F) in December and January. Nights drop to 15–18°C (59–64°F). Humidity is low and it almost never rains. Mornings want a light jacket; by lunch you are in shirt sleeves.

This is the season for the lower walking trails, golf, and cycling the lanes. The hot springs out towards Mae On are a short drive, and the warm water does stiff joints some good. The only drawback is the cool nights, if you are used to somewhere like Florida.

Hot and hazy: March to May

Daytime highs reach 34–37°C (93–99°F), April is usually the hottest month, and nights stay at 23–25°C (73–77°F). There is little rain until late May. The bigger problem is haze: agricultural burning in the valleys sends smoke across the region, and air quality in the city can be poor from March to mid-April.

Midday heat is draining at our age. The day rearranges itself around it: out early, out late, and in between you are in the pool or under a fan with a book. Out at the lodge, further east in open country, there is more breeze and the haze is noticeably thinner than in town, but it is still there.

Wet and green: June to October

Highs of 30–32°C (86–90°F), nights of 23–25°C (73–77°F), humidity around 80%. The rain mostly comes as short, heavy afternoon bursts that are over by evening, so mornings are usually bright. August and September bring longer spells of rain, and the roads get slippery.

Most people hear “monsoon” and book elsewhere, but for a long stay this is one of the easier and cheaper times to be here. Quick-dry shirts and light trousers do the job, with an umbrella kept in the scooter basket. The waterfalls run full and the countryside turns green. At the lodge, the covered seating around the restaurant and bar lets you sit outside while it rains.

Packing and health

For a first long stay, arrive in November or December. You start in the best of the weather and have time to decide whether to stay on into the hot months.

Pack cotton shirts, quick-dry trousers, comfortable walking shoes, one light jacket for December nights, and a small umbrella or packable rain jacket for the wet season. Heavy clothes can stay at home.

Drink more water than you think you need in every season, wear a hat from March to May, and bring a mask for the haze if smoke bothers you in March and April.

Compared with the beach resorts

Hua Hin and Pattaya are hotter and more humid all year, with less relief in the cool months. Phuket’s rainy season feels longer, and its crowds never really leave. Chiang Mai has proper seasons and cleaner air for most of the year, with March and April the exception.