Thailand and Chiang Mai have different weather patterns to Northern Europe and North America. There are three distinct seasons in Chiang Mai. These are the hot, rainy and cool seasons. The hot season generally stretches from early March to the end of May, the rainy season from July to late September or October and the cool season from then until the following February.
THE COOL SEASON
The cool season is when Chiang Mai and its environs are at their finest and is also the peak visitor season. Daytime temperatures averaging a balmy 25°C offer a wonderful respite from harsh northern hemisphere winters. Chiang Mai gets around nine hours of sunlight a day during the cool season and rain is a rarity.
Even at night, temperatures in the city rarely fall below 13°C and only require visitors to wear long trousers and jackets. The mountain regions around the city are colder at night and people staying at one of the many resorts nestled amid them will notice a difference. The cool season comes after the rainy season and the valley around the city is lush, green and an enchanting spectacle.
THE HOT SEASON
Lives up to its name and temperatures often hit 40°C and above, although the average daytime temperature is around the 35°C mark. The climate is less humid in Chiang Mai than in the southern regions around Bangkok and offers a more pleasant environment to take part in activities and go sightseeing. Haze generated by farmers burning stubble off their land is an issue some years. Low humidity levels can exacerbate this. Towards the end of the hot season there might be an occasional thunderstorm signalling the onset of the wet season.
THE RAINY SEASON
Offers a welcome respite from the heat of summer and cloudy skies are welcomed with open arms by tourists and residents alike. It does not rain for whole days at a time very often and the norm is two to three hours of heavy rain a day. The storms invariably freshen up the air. The downside of the storms is that the city’s drainage system does not cope with the runoff well and low-lying roads tend to remain flooded for hours afterwards. The rainy season is also when mosquitoes breed. The local tourism bureau recommends mosquito repellent and covering arms and legs to avoid being bitten.