Summer in Chiang Mai hits you with heat, humidity, and sudden, heavy rains that really change how you experience the city.
Daytime highs usually reach around 32–34°C (89–93°F), and you’ll probably get caught in an afternoon downpour, especially in August. The air feels thick, and the skies stay cloudy a lot, but the landscape turns a beautiful green this time of year.
Humidity climbs to its highest, often over 75%. That makes the warmth feel even more intense.
You get fewer hours of sunshine compared to the dry season, but the days are still long enough for exploring between showers.
This mix of rain and heat brings both hassles and some surprising rewards for travelers.
If you know what to expect from summer weather, you can plan better. It helps with packing, timing outdoor activities, and knowing when to slow down.
Understanding the usual temperatures, rainfall, and comfort levels makes it easier to set realistic expectations for your trip to northern Thailand.
Typical Summer Temperatures
Chiang Mai’s summer means hot days, warm nights, and some real shifts from early to late season.
You’ll feel high daytime heat, milder evenings, and the year’s hottest stretch in April before the rains show up.
Daytime and Nighttime Averages
During summer, daytime highs usually hit 34°C to 38°C (93°F–100°F).
April is the real scorcher, with averages close to the top of that range. The sun’s strong, and with barely any wind, afternoons feel hotter than the numbers suggest.
At night, things get a bit more comfortable. Temperatures drop to 23°C–26°C (73°F–79°F), so you’ll get some relief after a hot day.
Nights are still warm, though—don’t bother packing a jacket.
Humidity creeps up as May gets closer. That makes nights feel warmer and takes away some of the cooling you’d expect after sunset.
Monthly Variations in Temperature
Summer runs from March through May. Each month brings its own temperature pattern, and that really affects your comfort.
- March: Highs around 34°C–36°C, with nights near 21°C–23°C.
- April: The hottest month, averaging 37°C–38°C during the day and 24°C–26°C at night.
- May: Still hot, with highs around 33°C–35°C, and humidity jumps as the rainy season starts.
March feels hot but dry. April is just plain blazing and dry. By May, the highs dip a bit, but humidity takes over.
If you’re planning activities, mornings and evenings are definitely the most manageable times to be outside.
Temperature Extremes
Extreme heat happens a lot in Chiang Mai’s summer, especially in April.
Temperatures can shoot above 40°C (104°F) on the roughest afternoons. That doesn’t happen every day, but it’s common enough to mess with outdoor plans.
Summer nights almost never drop below 21°C (70°F). Chiang Mai’s tropical climate keeps nights warm, unlike places with big day-night swings.
Heat waves sometimes drag on for days. You’ll want shade, lots of water, and air conditioning to stay comfortable.
If you don’t handle heat well, avoid the midday hours. That’s when things get most intense.
Rainfall Patterns in Summer
Rainfall jumps up fast in Chiang Mai’s summer when the southwest monsoon arrives.
You’ll see frequent showers, high humidity, and a real shift from dry spring into the wettest stretch of the year.
Monsoon Season Overview
Summer in Chiang Mai runs from June through August, lining up with the southwest monsoon.
Moist air from the Indian Ocean brings heavy rainfall to northern Thailand, making these months the wettest.
Rain usually rolls in as afternoon or evening storms. These showers can be short but really intense, with thunder and lightning pretty common.
Even with all that rain, mornings often stay dry, so you can squeeze in outdoor plans before storms hit.
Humidity climbs to its highest in summer, often around 80%. Pair that with daytime highs above 30°C (86°F), and the air can feel sticky and heavy.
That’s just part of monsoon season in Chiang Mai.
Average Precipitation by Month
Rainfall totals rise steadily from late spring into mid-summer.
By June, you’re looking at about 125 mm (5 in) of rain for the month.
July bumps that up to around 140 mm (5.5 in).
August is the peak, averaging 217 mm (8.5 in)—the wettest month of the year.
Rain doesn’t spread out evenly. Some days get hammered with downpours, while others stay dry.
| Month | Average Rainfall |
|---|---|
| June | ~125 mm (5 in) |
| July | ~140 mm (5.5 in) |
| August | ~217 mm (8.5 in) |
These are long-term averages, so any given year might look a little different.
Frequency of Rainy Days
You’ll get rain on a lot of days during summer.
In June, Chiang Mai usually gets about 14 rainy days.
July averages 16 rainy days, and August tops out at 18 rainy days.
Rain rarely lasts all day. Storms usually come in bursts, often late afternoon or evening.
That gives you some flexibility—do your sightseeing or outdoor activities earlier.
With frequent showers and high humidity, you’ll want to prep for wet conditions almost every other day.
Pack lightweight rain gear, quick-dry clothes, and waterproof shoes if you want to stay comfortable.
Humidity and Comfort Levels
Chiang Mai’s summer brings high heat and humidity, and that combo really affects how you feel outside.
The air can swing from moderately dry to super damp, depending on the month.
Average Humidity Range
Humidity shifts through the year, but in summer it usually sits between 65% and 80%.
The lower end shows up in late spring. The peak hits during the wettest months, July and August.
At around 70%, the air feels sticky but it’s manageable if you stick to shade or catch a breeze.
Once humidity goes above 75%, sweat just won’t evaporate quickly, and the heat feels heavier.
Here’s a quick look at average humidity in summer:
| Month | Average Humidity |
|---|---|
| May | ~70% |
| June | ~73% |
| July | ~78% |
| August | ~81% |
You’ll notice the damp air, especially in the mornings and evenings when moisture hangs around.
Indoor spots with fans or air conditioning feel a lot better during these times.
Heat Index and Perceived Temperature
The heat index mixes air temperature with humidity to show how hot it really feels.
In Chiang Mai, summer highs often hit 34–38°C. With humidity above 70%, the perceived temperature can feel several degrees higher—sometimes more like 40°C.
You’ll feel this most in the afternoons when heat and moisture both peak.
Even if the thermometer says 36°C, your body might feel it as 41°C because sweat just doesn’t cool you off as fast.
Plan outdoor stuff for early morning or late evening if you can.
Wear light clothes, drink water often, and take breaks in the shade.
Some people find relief by staying near water or heading to higher elevations around Chiang Mai.
Sunshine and Daylight Hours
You’ll get long days and plenty of daylight during summer in Chiang Mai, but cloud cover and seasonal rains cut down on how much direct sunshine you actually see.
The balance between daylight length and sunshine hours really shapes your plans.
Average Daily Sunshine
During summer, Chiang Mai gets about 4 to 6 hours of direct sunshine per day.
June and July are the cloudiest, often dropping below 5 hours because of rain and clouds.
August is about the same, with sunshine averaging 4 hours per day.
Right before the summer rains, in April and May, you get 7–9 hours of daily sunshine.
Once the monsoon kicks in during June, the share of sunny hours drops fast, often below 40%.
So, expect a lot of overcast days in summer. Still, when the clouds break, the midday sun can be strong, so don’t skip sun protection.
Quick Reference (Average Sunshine Hours per Day):
- April: ~8h 48m
- May: ~7h 36m
- June: ~5h 40m
- July: ~4h 44m
- August: ~4h 25m
Length of Daylight
Daylight hours in Chiang Mai barely change through the year, thanks to its tropical location.
In summer, days last between 12 and 13 hours from sunrise to sunset.
June has the longest days, about 13 hours 13 minutes. August shortens a bit to around 12 hours 44 minutes.
So, you always get plenty of daylight for travel, sightseeing, or outdoor work, even if clouds hide the sun.
On average, daylight in summer breaks down like this:
- Sunny hours: 35–46%
- Cloudy or shaded hours: 54–65%
You’ll get a lot of daylight, but the actual brightness depends on rain and clouds.
Wind and Air Quality in Summer
Expect calm, humid conditions in Chiang Mai’s summer.
Winds stay light, and air quality can shift because of burning and heavy rain patterns.
Typical Wind Patterns
Winds in summer are usually light and variable.
Average speeds stay under 2 mph, with only the odd gust hitting 4–5 mph.
You won’t feel much of a breeze, so the air often seems still.
Since Chiang Mai sits in a valley, airflow is limited. That traps heat and humidity close to the ground, making afternoons feel even hotter.
Nights bring a bit of cooler air, but the lack of wind means it’s only a slight relief.
The southwest monsoon influences the area from May through September. This brings frequent rain, but not strong winds in the city itself.
You get short bursts of heavy rain, then it’s back to calm, muggy weather.
Air Quality Considerations
Air quality in Chiang Mai changes depending on the time of year.
Early summer can still have smoke from regional agricultural burning. That lowers visibility and bumps up fine particles in the air.
If you’re sensitive, take some extra precautions during these weeks.
Once the rains come regularly in June and July, rainfall helps clear pollutants out of the air.
Air quality usually improves then, though humidity stays high.
Keep in mind, low wind speeds mean less natural ventilation, so pollutants, cooking smoke, and car exhaust can linger longer in the city than in coastal areas.
If you want to be outside, check daily air quality reports to pick the best times.
What to Expect: Summer Weather Impact on Travel
Chiang Mai’s summer is the wettest time of year, with frequent afternoon and evening storms.
Rain is common, but it usually comes in short bursts, so you’ll still find dry windows for activities.
High humidity and warm temperatures shape how you plan your days and what you pack.
Best Activities for the Season
You can absolutely enjoy outdoor activities, but honestly, mornings work out best since rain usually holds off until later. Visiting temples, local markets, or even wandering through nearby villages feels ideal because you can duck inside fast if a sudden shower hits.
Nature trips? Totally doable, though you might find the trails a bit muddy. Waterfalls like Mae Sa or Bua Thong really come alive during the rainy season, so they’re great for quick hikes if you don’t mind getting a little messy.
If storms roll in, you’ve still got plenty of indoor options. Cooking classes, spa visits, or handicraft workshops all give you a taste of Chiang Mai’s culture without stressing over the weather.
For day trips, just remember that flooding sometimes closes rural roads. Stick to well-traveled routes, and it’s always smart to check the forecast before you head out.
Packing and Preparation Tips
Bring a light rain jacket or just grab a disposable poncho when you get there. An umbrella might help with drizzle, but once it really pours, you’ll want that jacket.
I always go for waterproof shoes or sandals that dry out fast. Heavy sneakers just aren’t worth the trouble.
Humidity gets intense, so stick with lightweight, breathable clothing. Cotton or moisture-wicking stuff usually keeps you from feeling sticky all day.
Toss a small dry bag in your pack to keep your electronics and papers safe from sudden rain.
Don’t forget insect repellent—mosquitoes seem to love the weather right after a storm. You still need sunscreen too, since the sun comes out between showers.
Try to keep flexible plans. Rain often just shows up for half an hour or so, then you can usually get back to whatever you wanted to do.