Thailand Chiang Rai Weather in September — Climate Guide
September in Chiang Rai is moderate
Chiang Rai Weather in September — Quick Answer
As of 2026- Avg temp
- 31° / 22°
- Rainfall
- 215mm · 20 days
- Crowds
- Quiet
As of 2026, Chiang Rai in September averages a high of 31°C and low of 22°C with 215mm of rain over about 20 days. Late wet season. Warm and humid (31°C), still very rainy. Light clothing, rain gear, and quick-dry footwear. Lush, clean-aired, and quiet — a good-value green-season month.
September is moderate for Chiang Rai.
September is still firmly in the wet season, nearly as rainy as August (around 215mm) with high humidity and days around 31°C. The landscape remains gloriously green, the waterfalls are full, and the air is clean and haze-free.
Like the other green-season months, it's quiet and cheap, with the temples and Golden Triangle uncrowded and hotel rates low. The rice terraces around the hills are lush and filling out ahead of the later harvest, making for excellent green scenery between the showers.
Travel score
Chiang Rai September Weather Stats
Avg High
31°C
Avg Low
22°C
Rainy Days
20
215mm total
Sunshine
5h
Daily avg
Humidity
82%
muggy
UV Index
8
Very high
Wind
5 km/h
Gusts 14
Crowds
Quiet
At attractions
September Sunrise & Sunset
Air Quality
PM2.5
18 μg/m³
PM10
35 μg/m³
Status
good
Feels-Like Temperature & Wind
Feels like
Daytime
35°C
Nighttime
23°C
Humidity and wind affect how the actual temperature feels.
Wind
5 km/h
Max gust 14 km/h
Activities Recommended for September
September Travel Pros & Cons
Pros
- Lush green scenery and full waterfalls
- Clean, haze-free air
- Low prices and few crowds
- Rains begin tapering late month
Cons
- Still very rainy
- High humidity (82%)
- Muddy rural roads
- Occasional washed-out days
September Events & Festivals
- Late wet season — still frequent rain
- Lush green hills and full waterfalls
- Clean air, low prices, few crowds
- Rice terraces filling out before harvest
Chiang Rai in September — Full Picture
September is still firmly in the wet season, nearly as rainy as August (around 215mm) with high humidity and days around 31°C. The landscape remains gloriously green, the waterfalls are full, and the air is clean and haze-free.
Like the other green-season months, it's quiet and cheap, with the temples and Golden Triangle uncrowded and hotel rates low. The rice terraces around the hills are lush and filling out ahead of the later harvest, making for excellent green scenery between the showers.
Rain still comes mostly as heavy afternoon and evening bursts, so morning sightseeing works. The downsides remain the humidity, the occasional washed-out day, and muddy rural roads to the more remote sights. Toward the very end of the month, the rains begin to taper as the cool season approaches.
Pack light clothing, rain gear, and quick-dry shoes, and stay flexible. Late September can start to feel like the turn toward the better-weather months ahead.
What to Wear & What to Pack
Late wet season. Warm and humid (31°C), still very rainy. Light clothing, rain gear, and quick-dry footwear. Lush, clean-aired, and quiet — a good-value green-season month.
Packing Checklist
Seasonal Weather Overview
Spring (Mar·Apr·May)
34.3°C
21°C
7.7/mo
Summer (Jun·Jul·Aug)
31.7°C
23°C
19/mo
Autumn (Sep·Oct·Nov)
Current30.3°C
20°C
12/mo
Winter (Dec·Jan·Feb)
28.7°C
14.7°C
1.3/mo
Chiang Rai Monthly Weather Comparison
| Month | High | Low | Rain | Sun | Humid | UV | Crowd | Price |
|---|---|---|---|---|---|---|---|---|
| January (Best) | 28° | 14° | 1d·10mm | 9h | 65% | 8 | Very busy | Peak |
| 31° | 16° | 1d·10mm | 9h | 60% | 9 | Busy | Peak | |
| 34° | 18° | 2d·20mm | 8h | 55% | 10 | Quiet | Low season | |
| 36° | 22° | 5d·60mm | 8h | 60% | 11 | Moderate | Shoulder | |
| 33° | 23° | 16d·200mm | 6.5h | 75% | 9 | Quiet | Low season | |
| 32° | 23° | 17d·160mm | 5.5h | 78% | 9 | Quiet | Low season | |
| 32° | 23° | 19d·190mm | 5h | 80% | 9 | Quiet | Low season | |
| 31° | 23° | 21d·230mm | 4.5h | 82% | 8 | Quiet | Low season | |
| 31° | 22° | 20d·215mm | 5h | 82% | 8 | Quiet | Low season | |
| 31° | 21° | 12d·110mm | 6.5h | 78% | 8 | Moderate | Shoulder | |
| November (Best) | 29° | 17° | 4d·40mm | 8.5h | 70% | 8 | Busy | Peak |
| December (Best) | 27° | 14° | 2d·15mm | 8.5h | 68% | 7 | Very busy | Peak |
View Other Months
Chiang Rai September Hotel Picks
Frequently Asked Questions
Is September a good time to visit Chiang Rai?
Chiang Rai in September is moderate. Tourist crowds are quiet and flight/hotel prices are low season.
What's the average temperature in Chiang Rai in September?
Chiang Rai September averages a high of 31°C and a low of 22°C.
Does it rain much in Chiang Rai in September?
Chiang Rai September averages 215mm of rainfall over about 20 rainy days.
What should I wear in Chiang Rai in September?
Late wet season. Warm and humid (31°C), still very rainy. Light clothing, rain gear, and quick-dry footwear. Lush, clean-aired, and quiet — a good-value green-season month.
What time are sunrise and sunset in Chiang Rai in September?
Chiang Rai September sunrise is 05:55 and sunset is 18:10, with 12h 15min of daylight.
What's the air quality like in Chiang Rai in September?
Chiang Rai September air quality (AQI) averages 42, rated Good. PM2.5 averages 18μg/m³.
What activities are recommended in Chiang Rai in September?
In September, Chiang Rai is great for Waterfalls and green tea country, Rice terraces (lush and green), Temples (morning sightseeing).
Is September peak season in Chiang Rai?
Chiang Rai September crowds are quiet and prices are low season. You can travel relatively comfortably without long queues.
Best Months to Visit Chiang Rai
View Other Months
Planning a September trip to Chiang Rai?
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Why you can trust weather guide
Based in Chiang Mai for 8+ years, with 30+ countries visited across Southeast Asia, Japan, and Europe. Every detail in this guide is primary-source verified as of April 2026, with prices auto-refreshed via live exchange rate APIs. This isn't AI-generated boilerplate — it's written from the perspective of someone who has actually been there.