The mountains and valleys of Chiangmai province make this part of Thailand different of weather from another parts of Thailand. In fact, if you tell someone, who live in Bangkok or the southern Thailand that you are going to Chiang Mai, they’d almost absolutely say cold but it not cold for at all ha…ha, as if it were some frozen Arctic wasteland (any temperature below 75F seems to qualify as freezing to many Thai people!) It’s true that temperatures in the villages high in the mountains can be cold at night during the cool season, but the city of Chiang Mai and the surrounding valley enjoys warm/hot days and pleasantly cool evenings for much of the year.
November-February sees relatively low humidity, comfortable temperatures and low amounts of rainfall. Festivals in the cool season include Loy Krathong and Yi Peng Festivals (November) and the Chiang Mai Flower Festival (February). Visitors to Chiang Mai in the cool season may find a light jacket or shawl useful in the evenings when temperatures can chill off.
March-June can be extremely hot at times with temperatures hovering around 40°C. March often sees the worst of the haze which can affect large parts of the north of Thailand as farmers burn their crops and the smoke is trapped in the low-lying valleys. April sees thousands of Thai and foreign tourists descend on the city to celebrate the world-famous Songkran Water Festival which heralds the Thai New Year.
July-October is low season in terms of tourists which also means bargains to be had in terms of accommodation and flights. Rainy season has the advantage of seeing the countryside at its greenest and waterfalls in full flow. It doesn’t rain every day and even when the heavens do open you can expect to see plenty of sunshine in between the showers.
Humidity levels in Chiang Mai and surrounding areas are noticeably lower than Bangkok and some of the southern resorts in the Gulf of Thailand and on the Andaman Coast. Nevertheless, the humidity level during March-November can be high usually peaking in May.
In the table below I’ve listed the regular temperatures and amount of rainfall during the year for Chiang Mai. I’ve also detailed some other factors to reflect including humidity levels, geographical location and local festivals which all may have a bearing on when you wish to visit Chiang Mai. Please note that Chiang Mai is the name of the city and province; temperatures in the countryside and mountains (particularly at night) tend to be cooler than the city.