Weather in Chiang Mai in May

The month to avoid. May is the month most people should skip in Chiang Mai. You should expect rain on 22 days of the month, which is more days wet than dry.

May ranks 11 of 12 — near the bottom of Chiang Mai's year. December is the month that works, and the swing between the two is 64 points, which is a different holiday rather than a slightly better one.

Rain on 22 of the month's 31 days, 6 of them heavy. At that frequency a wet-weather backup is not a contingency, it is the itinerary — book the indoor things first and treat the clear days as the bonus. Pack for heat management rather than style: shade, water, and a schedule that gives up on the middle of the day.

What the averages hide

Averages flatten a month, and this one hides a few things: 13 days clear 35 °C, so a serious heatwave is normal rather than notable. Across the twenty years measured, the hottest May day reached 42.8 °C and the coldest night fell to 19.2 °C, and the wettest single day dropped 68 mm — roughly 36% of the month's rain in one day.

May is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest May on record still delivered 310 mm against 81 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 189 mm average is a reasonable planning figure, not a promise.

Wind is light at 0.1 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 75%, high enough to notice on the warm days without dominating them.

How May sits in the year

Temperatures hold steady either side: 37.3 °C in April, 34.4 here, 32.9 in June. Nothing about the timing within the month matters much. Rain has already shifted: 12 days more than April had.

Daylight in May

May is at or near the longest days of Chiang Mai's year: 13 hours of daylight, gaining 0.4 hours across the month. Evenings are the real gain — dinner outdoors still happens in full light.

An inland climate

Despite being inland, the year stays fairly even: 20.8 °C between the year's warmest afternoons and coldest nights.

How busy it gets

Off season. The genuine off season: cheapest by a distance, with the caveat that some tours and restaurants close entirely.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

May in Chiang Mai versus nearby

If Chiang Mai is one option among several, the nearby comparison is worth making. Luang Prabang is close enough to be a coin toss — within a degree on temperature, 4 days less rain. Udon Thani is close enough to be a coin toss — within a degree on temperature, the same number of rain days.

So: May is a compromise. December is 62 points better and is what Chiang Mai is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Chiang Mai

See all twelve months in Chiang Mai, or where else to go in May.