When we decided to move to Thailand we’d already done plenty of homework so we I can’t say that we are surprised by the smokey season but experiencing it, puts it in a different perspective. We’re only a couple weeks into it and it is getting noticeably worse as the weeks progress. From what we are seeing on various Facebook groups, it appears to be worse in Chiang Mai than it currently is in Chiang Rai, however I wouldn’t be outside doing any cardiovascular activity in either city at the moment. It reminds me a little of the smog alerts we would get in Los Angeles County in the late 70’s, albeit a little more serious. Apparently this time is also used to burn a lot of household trash, including plastics resulting in fine particulates and dust that can be quite harmful to people with sensitivities. It’s sure made for some pretty sunsets but that is no trade-off. We’ll definitely use the burning season as an opportunity to travel next year.
If you or someone you know is considering traveling to Northern Thailand, I would avoid March altogether.