The March weather guide for Thailand shown below is for Bangkok. Weather in Thailand in March. The average maximum daytime temperature in Thailand in March is a hot 34°C (93°F) with very high heat & humidity. There are usually 8 hours of bright sunshine each day, which represents 70% of the 12 hours of daylight. Expect 31mm (1.2 inches) of rainfall across the whole of March with 3 days with some rain falling. Maximum UV levels will be extreme (11+ UV index) at midday when the skies are clear. The average night-time temperature is usually a warm 25°C (77°F). The weather in Thailand in March is represented by Bangkok.