Not just the temperature. What each month actually changes about a trip, and the ones we would pick.
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Most answers to "when should I go to Chiang Mai?" are a temperature chart. Temperature is only a small part of the answer. What actually changes a trip from one month to the next is the air, the rain, which festivals fall when, which trails are open, and how full and expensive the city is.
This guide takes the year one month at a time, with a verdict for each. "Our pick" means we would choose it, "Good" means good with a small catch, "Mixed" means the catch is real and you should know it before booking, and "Avoid if you can" means just that. February and April get a qualified verdict of their own. Temperatures and rainfall are the Thai Meteorological Department's 1991–2020 averages for Chiang Mai. Several festivals follow the lunar calendar and move from year to year. We give their usual timing, and an exact date only where it changes how you plan.
The short answer
If you can choose, come between November and mid-February. The days are dry and warm, the nights are cool, and the mountains are usually clear. It is also high season, when hotels fill up and cost more than in the low season, so book early, especially for the Yi Peng full moon in November and for Christmas and New Year.
If you can avoid it, do not come in March. It is hot, and it is most often the worst month of the smoke season, when smoke from forest and farm fires collects in the valley. April is not reliably better. Come then only if Songkran is the reason for your trip.
The green season, from June to October, is better than its reputation. It rains on many days, most of all in August and September, but usually in a heavy burst rather than all day. The countryside is at its greenest, and hotel prices are lower than in high season. You trade some flexibility for that: a few mountain trails close, and a wet afternoon can end an outing.
The year at a glance
One line per month. Our verdict sits in the second column, and the month's name takes you to its full entry further down.
Dry and sunny. About 30 °C by day, 16 °C at night. Usually clear air, but not every year.
The coldest mornings in the mountains, with frost on Doi Inthanon on some days. Bo Sang umbrella festival, usually the third weekend. Mountain roads busy at weekends.
Very hot until the first storms. The air usually clears once the rain sets in.
Low season: fewer visitors and lower prices than in the cool months. The Inthakhin city pillar festival usually falls in May or early June. The Kew Mae Pan ridge trail on Doi Inthanon is open until 31 May.
Songkran, 13 to 15 April. Accept the heat, and possibly the smoke.
November to February: the cool season
The rains usually end in late October, and the next three and a half months, roughly, are what most people picture when they think of Chiang Mai: blue skies, temperatures around 30 °C by day, and nights cool enough for a light jacket. Up in the mountains it is properly cold. On Doi Inthanon, Thailand's highest peak, early mornings can fall close to freezing in December and January.
The catch is that everyone else knows this too. This is high season for foreign visitors and for Thai holidaymakers, who come north for the cold. Hotels fill, prices rise, and the mountain roads are busy at weekends.
Loy Krathong, in November: a krathong set afloat after dark.
Our pick. About 31 °C by day, 20 °C at night, 41 mm of rain.
The first mostly dry month of the season, the landscape still green from the rains, and the north's biggest festival. Yi Peng and Loy Krathong fall on the full moon of the twelfth Thai lunar month, which is 24 November in 2026. The city sets its programme around that date each year. For about three nights, the temples hang lanterns and the river fills with krathongs, the small candle-lit floats of Loy Krathong. The famous mass releases of sky lanterns are separate, ticketed events held outside the city on dates set by their organisers, not something you see over the old city. In 2027 the full moon is expected in mid-November; the exact date has not yet been officially confirmed. Hotels near the old city fill months ahead for those dates, so book early or come for the rest of the month instead. The Kew Mae Pan nature trail, a ridge walk near the summit of Doi Inthanon, reopens on 1 November, and morning mist starts to settle in the mountain valleys.
December
Our pick. About 29 °C by day, 17 °C at night, 14 mm of rain.
The coolest days of the year and usually the clearest views. It is one of the two best months for the mountains, with January, if you bring something warm: on Doi Inthanon, it is often only a few degrees above zero at sunrise. From Christmas into New Year, hotels fill and prices rise, so book well ahead. The public holidays on 5 and 10 December often make long weekends, which also fill hotels and mountain resorts.
Our pick. About 30 °C by day, 16 °C at night, 11 mm of rain.
Still dry and clear, with the coldest nights of the year. On Doi Inthanon, frost forms on grass on some mornings, which draws Thai visitors in large numbers. The Bo Sang umbrella festival, east of the city, usually takes the third weekend of the month. Wild Himalayan cherry trees flower in the hills, usually in January, at Khun Wang, near Doi Inthanon, and at Doi Ang Khang, three to four hours north of the city. With fewer holiday weekends than December, it is our pick for hiking on Doi Inthanon. The air is usually clean, but not in every year: in some seasons the first smoky days come in January.
February
Good in the first half. About 33 °C by day, 17 °C at night, 10 mm of rain.
Two different months. The first half is often still clear. From mid-month, the smoke season usually starts to build, and by the last week, views from Doi Suthep, the mountain above the city, can be grey. The Chiang Mai Flower Festival, with its parade of flower floats, usually takes a weekend in early February, sometimes later in the month. Chinese New Year, in late January or February, brings extra visitors.
March to May: the hot season
From around mid-February, the heat builds and the smoke season settles in. Every dry season, smoke from forest fires and burning fields, some of it from across the border, collects in the valley that holds Chiang Mai. March is most often the worst month. The start, the end and the severity of the season change from year to year, and our smoke season article covers how to read the air and when to move your dates.
The rains bring it to an end. The first storms usually arrive in late April or May, and once they settle in, the air clears and the landscape turns green again.
Avoid if you can. About 35 °C by day, 20 °C at night, 20 mm of rain.
Hot, dry, and most often the smokiest month of the year. On bad days the mountains around the city disappear, sunsets turn a dull orange, and the air is a real problem for sensitive groups: people with asthma or a heart or lung condition, children, older people and pregnant women. In bad years, the smoke keeps some visitors away. If March is the only month you have, come anyway, but check the air each morning and plan outdoor days around it.
April
Only for Songkran. About 37 °C by day, 23 °C at night, 54 mm of rain.
The hottest month, and the smoke is often still there. Its one great reason to come is Songkran, the Thai New Year, on 13, 14 and 15 April. In Chiang Mai it is a water festival on a citywide scale: people throw water at each other along the moat and the main streets for several days, and in town the water fights often start a day before the official holiday and carry on a day after. It is joyful and impossible to stay dry. Hotels fill for those days, so book ahead.
May
Mixed. About 35 °C by day, 24 °C at night, 168 mm of rain.
It starts very hot and gets better as the first storms arrive. Once the rains set in, usually in the second half of the month, the air clears and the hills turn green. It is low season, with fewer visitors and lower hotel prices than in the cool months. Inthakhin, the festival of Chiang Mai's city pillar at Wat Chedi Luang, follows the northern lunar calendar, so its dates move each year; it usually falls in May or early June. The Kew Mae Pan trail on Doi Inthanon stays open until 31 May.
June to October: the green season
Travel sites call this the rainy season, and it does rain, most of all in August and September: August, the wettest month, averages about 220 mm. But rain here rarely lasts all day. The typical pattern is a dry morning, a heavy storm in the afternoon or evening, then a clear spell. Plan outdoor things for the morning and you lose much less than the numbers suggest.
In return you get the greenest countryside of the year, waterfalls at full strength, rice fields from planting to harvest, fewer visitors and lower hotel prices than in high season. The costs are real too: some national park trails close for the season; forest trails are often muddy, with leeches; mountain roads can be cut by landslides after heavy storms; and in some years the Ping River, which runs through the city, floods: more on that under September.
June
Good. About 33 °C by day, 25 °C at night, 118 mm of rain.
The start of the green season and one of the best value months. Showers are frequent but usually short, the air is clean, and the countryside turns green fast. Hotels and tours are quiet. The Kew Mae Pan trail on Doi Inthanon closes from 1 June to 31 October, though the summit and the twin royal pagodas stay open.
July
Good. About 32 °C by day, 24 °C at night, 149 mm of rain.
Farmers plant rice in the valleys. Khao Phansa, the start of the three-month Buddhist Lent, falls the day after Asanha Bucha, a full-moon holiday, usually in July and in some years in early August. Temples hold processions of large carved candles. On both days, as on the other main Buddhist holidays, alcohol sales are banned across Thailand, with some exemptions for licensed hotels and venues since 2025, so expect most bars and shops not to sell or serve alcohol.
August
Mixed. About 32 °C by day, 24 °C at night, 223 mm of rain.
The wettest month, and the one where rain most often spoils a plan. It is also when the rice terraces are at their greenest and the waterfalls start to pound. Expect mud, and often leeches, on forest walks, and treat river activities with care after a heavy night of rain: water levels rise fast.
September
Mixed. About 32 °C by day, 24 °C at night, 207 mm of rain.
Nearly as wet as August, and a quiet month, with low-season prices. It is also when the Ping River is most likely to flood, from late in the month into early October. Most years pass without serious flooding in the city, but not all: in late September and early October 2024, the river burst its banks and water reached the Night Bazaar area and Warorot Market, while the old city stayed dry. If you come in September, keep your plans flexible and follow local news.
October
Good. About 32 °C by day, 23 °C at night, 124 mm of rain.
The rains ease through the month and the mornings start to turn cooler, earlier in some years than others. The landscape is still fully green and the waterfalls are at full flow, with the crowds of high season still a few weeks away. Holidays can still fill some dates: China's National Day week at the start of the month, and Chulalongkorn Day on 23 October, which makes a long weekend in some years. Ok Phansa, the end of Buddhist Lent, usually falls in October, with merit-making at the temples. Early October can still flood, as it did in 2024. Rice turns gold in the terraces towards the end of the month.
Five active days out, from Mae Taeng quad tracks and ziplines to bamboo rafting.
Common questions
What is the best month to visit Chiang Mai?
November, December and January, with the first half of February close behind. They are dry, warm by day and cool at night, and the air is usually clean. They are also high season, with more visitors and higher hotel prices than in the low season, so book early.
Is the rainy season a bad time to go?
Not necessarily. From June to October it rains on many days, most of all in August and September, but usually in a heavy afternoon storm rather than all day. You get green landscapes, full waterfalls and lower prices. Some trails close, forest walks are muddy, and the Ping River can flood from late August to early October, most often in late September and early October.
When is Chiang Mai cheapest?
Outside high season. From May to September, hotel prices are usually lower than from November to February. Which month is cheapest varies with the year and the hotel.
How cold does it get in Chiang Mai?
In the city, nights average 16 or 17 °C in December and January, which feels chilly after a hot day, and a cold spell can push them lower. In the mountains it is much colder: on the summit of Doi Inthanon, early mornings can be close to freezing. Bring a warm layer for any sunrise trip.
Is March really that bad?
Most years, yes. March is usually the peak of the smoke season, with poor air and lost mountain views on many days. The severity changes from year to year, and some years are much milder than others, but we would not choose March for a trip.
