Burning Season in Chiang Mai – Everything you need to know

Published by Thailand Hilltribe Holidays

What is the burning season in Chiang Mai ?

The burning season in Chiang Mai happens every year, and is caused by ‘slash and burn’ farming (an ancient agricultural practice) used by farmers across northern Thailand. Under this method, locals and farmers will burn leftover crops to prepare the soil for the next season of crops. It is a cost-effective way to clear the land and fertilise the soil. As this method is very cost-effective, farmers continue to adopt this practice despite the negative environmental and health benefits. The widespread burning creates a thick smog and massive air pollution issues for the whole of northern Thailand, which is now known as the ‘burning season’ or ‘smoky season’.

When is the burning season ?

Although some agricultural burning starts as early as January it typically does not become a concern until late February when the PM 2.5 levels (a measure of air pollution) start to reach unhealthy levels. They continue to stay at these levels until the end of April.

Historically it is common for there to be short rainstorms just after the Songkran (Thai New Year) Festival which takes place during 13-15^th of April. These rains typically clear the skies and so by the third week of April the air pollution is markedly improved.

Should I be concerned about the burning season?

This pollution and high PM 2.5 levels during the smoky season, can aggravate and trigger symptoms in those with respiratory conditions such as asthma, COPD, and emphysema. It can also cause short-term symptoms such as irritated eyes, a sore throat, runny nose, coughing, sneezing, and even shortness of breath. However some individuals may not show any symptoms or suffer any side effects.

In the long term, the smoke from these fires contains fine particulate matter (PM2.5) which enter the respiratory system and blood stream causing harmful short and long term effects.

How bad is the burning season?

If we are looking at figures, then you will see from historical data that the burning season and air pollution across northern Thailand is consistently bad during the same period each year; typically the end of February through to April.

There have been some years where the pollution levels have not been as high as other years, or where the season has been much shorter than other years. Nobody is able to predict how bad the burning season will be for any given year.

From a tourist’s perspective, it’s hard to say how bad the burning season will be for any individual traveler. This is because the burning season affects people in different ways. For some it may not affect their holiday at all, with only the hot weather and high temperatures posing a problem. Whereas for others if they experience physical side effects from the pollution, it can negatively impact their travels.

Burning Season Chiang Mai Historical Data

Should you visit Chiang Mai during burning season?

It depends….. if you suffer from chronic respiratory conditions then it’s advisable to avoid northern Thailand during this season. The burning season affects individuals very differently (even for the locals). Some people may not show any symptoms at all, and others may suffer chronically from adverse effects. So, it is very hard to say whether you should visit or not. We do suggest however, that it is best if you can plan your travels to northern Thailand for another time of year. Check out our post – When is the best time to visit Chiang Mai ?

Does the burning season affect the whole of northern Thailand? Are there any parts that are not affected?

Unfortunately there are no parts of northern Thailand that are unaffected by the burning season. The provinces of Chiang Mai, Chiang Rai, and Mae Hong Son are all affected by bad air pollution and high PM 2.5 levels. The skies are hazy and visibility of mountains and views are greatly reduced. Even at higher altitudes such as Doi Inthanon mountain, the haze and air pollution is still a problem. Note that the burning season takes place not only in northern Thailand, but also in neighbouring countries such as Laos, Myanmar and across many other South-East Asian countries.

Hazy skies, burning season in Chiang Mai

Where to go in Thailand during burning season?

In terms of air quality and weather, the Andaman coast (parts such as Phuket, Krabi, Koh Lanta, Similan islands) or the Gulf coast (Koh Samui, Koh Samet, Koh Chang) are all great places to visit during March and April.

Tips for burning season

If you do visit northern Thailand during burning season, it’s advisable to wear an N95 mask that filters out PM 2.5 particles. The regular medical masks do not filter out PM 2.5 so will not help protect your health. You may also want to download the AQI app which gives localised hourly updates about the air quality levels.

What is PM 2.5?

PM 2.5 is one type of pollutant that raises the most concern when people talk about the burning season in Chiang Mai. PM 2.5 refers to particulate matter in the air with a diameter of less than 2.5 microns. The particles are so small they can only be seen with an electron microscope and are small enough to enter our lungs and bloodstream. PM 2.5 is not a single pollutant, but a mixture of chemical pollutants.

What is AQI ?

The AQI (or Air Quality Index) is a yardstick measurement that looks at several different types of pollutants including PM 2.5. To put it simply, PM2.5 is a definite value and AQI is an index that measures many different types of pollutants and is calculated based on various standards.

Chiang Mai Weather by Month