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Pai sits in a mountain valley in northern Thailand at roughly 510 m (1,670 ft) above sea level, in Mae Hong Son Province about 135 km (84 miles) northwest of Chiang Mai. That elevation is the whole story behind Pai’s weather: unlike the hot, humid south of Thailand, Pai gets genuinely cool nights from November to February, and its dry season runs a full six months. The town averages around 1,297 mm of rain a year, almost all of it dumped between May and October. This guide breaks down Pai weather by month so you know exactly what to pack.
Pai Weather by Month: The Dry Season (November to April)
The dry season is why most people come. From November to April, days are sunny and rain is rare. December and January are the coolest months: average highs sit around 29°C (84°F) in December, but nights drop to an average low of 14.5°C (58°F) in January, and cold snaps can push early-morning temperatures down to 5 to 8°C (41 to 46°F). You’ll want a sweater and long trousers after sunset. By April the heat peaks: the average high reaches 38.9°C (102°F), and burning-season haze from northern Thailand’s crop fires can reduce visibility in late February and March. The best time to visit Pai for clear skies is November through January, before the heat and smoke build, and December and January are also when Loi Krathong and New Year fill the valley, so check the Pai events and festivals calendar if you want to time your trip around them.
Pai Weather by Month: The Rainy Season (May to October)
The southwest monsoon arrives in May and runs through October. Rain builds gradually: May sees about 169 mm, then August is the wettest month of the year at 258 mm, with rain falling on roughly 21 days. Rain usually comes in afternoon or evening downpours rather than all-day drizzle, so mornings stay usable for most of the season. Humidity climbs to 83 to 84% in July and August. Temperatures stay warm, with highs around 32°C (90°F) and lows near 23°C (74°F). Roads to the waterfalls and viewpoints on our things to do in Pai list get muddy, so plan outdoor trips for mornings in these months. September and October taper off to around 200 mm and 117 mm as the monsoon retreats.
Pai Weather by Month: Temperatures and Rainfall Table
| Month | Avg High | Avg Low | Rain (mm) | Rain Days |
|---|---|---|---|---|
| January | 29.8°C (86°F) | 14.5°C (58°F) | 11 | 1 |
| February | 33.3°C (92°F) | 14.7°C (58°F) | 6 | 1 |
| March | 36.9°C (98°F) | 18.2°C (65°F) | 19 | 1 |
| April | 38.9°C (102°F) | 22.9°C (73°F) | 60 | 4 |
| May | 36.3°C (97°F) | 23.9°C (75°F) | 169 | 14 |
| June | 33.6°C (92°F) | 24.0°C (75°F) | 180 | 17 |
| July | 32.4°C (90°F) | 23.7°C (75°F) | 226 | 20 |
| August | 32.1°C (90°F) | 23.5°C (74°F) | 258 | 21 |
| September | 32.9°C (91°F) | 23.3°C (74°F) | 200 | 16 |
| October | 32.7°C (91°F) | 22.2°C (72°F) | 117 | 10 |
| November | 31.0°C (88°F) | 19.4°C (67°F) | 40 | 3 |
| December | 28.8°C (84°F) | 16.2°C (61°F) | 11 | 1 |
Annual rainfall totals about 1,297 mm, concentrated in just six months. The four wettest months, June through September, account for roughly 70% of the yearly total. If you’re deciding where to base yourself for the wet season, see our where to stay in Pai guide for the areas that stay driest and easiest to get around.
Pai Weather by Month: What to Pack
Pack for two seasons at once if you’re visiting in November to February: shorts and t-shirts for 30°C (86°F) afternoons, plus a fleece or light jacket for 14°C (58°F) nights. Bring a rain jacket or compact umbrella from May to October, and closed shoes that can handle mud if you plan to walk the waterfall trails. Sunscreen and a hat are essential from March to May, when the UV index sits at 11 or higher most days. For the drive from Chiang Mai and scooter advice, read our Pai travel tips page.
Whatever the month, start from the main Pai travel guide for the full picture, and use our Pai’s neighborhoods guide to pick a base close to what you plan to do.
