The Bangkok Post reports that Thai Airways has canceled flights between Chiang Mai and Mae Hong Son due to high haze levels. The haze results from field burning, and is a common problem at this time of year. Flights will resume once the smoke clears, which might be in a day or two, or when the rains come in the next month or so.
If you were planning on flying to Mae Hong Son in the near future, keep an eye on your flight status, and think about a plan ‘B’.