Cool Season : (late October to end of February). Average temperature 21 C. and much cooler at night. The coolest months are December and January.

Hot Season : (early March to end of May) Average temperature 29.9 C. The hottest month is April

Rainy Season : (early June to end of October). Average temperature 25.5 C. The wettest month is September.      

Average Conditions for Chiang Mai

Month Average Sunlight (hours) Temperature Discomfort from heat & humidity Relative humidity Average Precipitation ( mm ) Wet Days (+0.25 mm ) Average Record Max Min Max Min am pm Jan 9 13 29 6 36 Medium 96 52 0 0.5 Feb 9 14 32 9 36 Medium 93 44 10 1 March 9 17 34 13 39 High 88 40 8 2 April 9 22 36 15 41 High 88 49 36 5 May 8 23 34 19 41 Extreme 90 60 122 12 June 6 23 32 21 38 High 92 67 112 15 July 5 23 31 19 37 High 94 69 213 21 Aug 4 23 31 21 37 High 95 73 193 20 Sept 6 23 31 18 36 High 96 72 249 17 Oct 7 21 31 16 36 High 96 69 94 8 Nov 8 19 30 12 37 High 96 63 31 4 Dec 9 15 28 6 36 Medium 96 57 13 2