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Bangkok Burning Season: What to Know About Air Quality

Bangkok burning season runs January to April. PM2.5 spikes and some days you should stay inside. Here is what to expect and how to protect yourself.

Bangkok Burning Season

Every year between January and April, air quality in Bangkok gets bad. How bad depends on the year, the wind, and how much farmers are burning. Here’s what you need to know.

What causes it

Farmers across northern Thailand, Myanmar, and Laos burn crop fields to clear land between harvests. The smoke drifts south and Bangkok gets it.

When it happens

The season runs roughly January through April. Peak is usually February and March. Some years are worse than others depending on rainfall and wind direction.

Bangkok is manageable but you’ll still have days where the air looks hazy and your eyes and throat feel it.

2025 JanFebMarAprMayJunJulAugSepOctNovDec MTWTFSS

Daily Air Quality Index (AQI) for Bangkok in 2025. Source: IQAir Bangkok.

What the numbers mean

The measure you want to watch is PM2.5. Those are tiny particles small enough to get into your lungs. The Air Quality Index (AQI) scale goes from 0 to 500. A rough guide:

0–50 Good
51–100 Moderate
101–150 Unhealthy for Sensitive
151–200 Unhealthy
201–300 Very Unhealthy
301+ Hazardous

Bangkok usually stays in the 100 to 150 range during peak season. Bad days push higher.

Bangkok Average AQI by Month (2025)

0 25 50 75 100 125 150 129 Jan 115 Feb 102 Mar 72 Apr 63 May 59 Jun 63 Jul 51 Aug 54 Sep 64 Oct 76 Nov 89 Dec AQI
Good (0–50) Moderate (51–100) Unhealthy for Sensitive Groups (101–150) Unhealthy (151–200) Very Unhealthy (201–300) Hazardous (301+)

Source: AQICN Bangkok. Monthly averages from daily readings.

What to do

Get an air purifier. This is the most effective thing you can do. Any model with a true HEPA filter works. Run it in your bedroom at night especially.

Close your windows. On bad days, keep them shut and run your AC on recirculation mode so it is not pulling in outside air.

Wear an N95 or KN95 mask outdoors. A regular surgical mask will not filter PM2.5. The N95 or KN95 will.

Check the AQI before outdoor plans. If you run, cycle, or do anything active outside, check first. Above 100 is worth rescheduling.

Don’t panic. Bangkok’s burning season is real but liveable. Most days during the season are fine and it ends by May.

Resources

  • IQAir Bangkok — real-time AQI and PM2.5 readings
  • AQICN Bangkok — real-time monitor with a useful map view
  • Air4Thai — Thailand’s official Pollution Control Department monitoring site