What happens each year
Press reports place northern Thailand's fire season in the dry months, with the peak in February and March and a fade when the rains arrive around May.
In the worst weeks, haze from crop burning and forest fires pushes air pollution to hazardous levels. In early April 2026, Chiang Mai briefly ranked as the most polluted major city in the world.
Closures in recent years
- 2023: the government closed 89 national parks to curb wildfires and dust.
- April 2026: Nan ordered nine national forest reserves closed, with fines of up to 200,000 baht.
- Doi Suthep-Pui, near Chiang Mai, has also been closed until the end of April in a past burning season.
- Northern provinces have been ordered to halt burning activities in past seasons.
What this means for our destinations
Chiang Rai, Nan and Mae Hong Son are in the north, so the best months we list for them (November to January) fall before the burning season. The reports we found focus on the upper north, so Khao Yai and Khao Kho are less affected, but check notices for any park before you go.
Planning rules of thumb
- Choose November to January for the north if you can.
- If you must go between February and April, check park closures and air-quality readings in the week you travel, and be ready to postpone.
- Never light open fires. Many parks ban bonfires, and burning bans have covered northern provinces.
Sources
- Khaosod English: government closed 89 national parks (2023)
- The Star: Nan orders closure of nine national forests (April 2026)
- NST (AFP): Thailand chokes on toxic haze (April 2026)
- Nation Thailand: Doi Suthep-Pui closed until April-end
- Pattaya Mail: northern provinces ordered to halt burning
- Bangkok Post: haze and blazes hit the North
How this was written
Drafted with AI assistance from the official and press sources listed below. We add our own trip notes as we test routes. Rules and closures change, so always confirm with the park.