Predicting the start, the intensity, the duration, of the smoke/smog hot season in Chiang Mai or mainland SE Asia is like predicting the weather. Your date Feb 22 stands at the cusp of the hot season smog season. Last year was exceptionally bad. Will it be the same? Better, worse? If you are concerned, why not make plans now for an alternative. Say islands or beaches on the Andaman sea.

I am travelling to Thailand for a month in August before moving on to the rest of Southeast Asia, a lot of this time will be spent in the north and particularly Chiang Mai. I am fully aware that this is monsoon season and I feel that this fact will only heighten my experience, one of the things I am interested in though is jungle trekking around Chiang Mai - is this still possible in August with it being monsoon? Now I know it won't be raining constantly but is it still possible to book organised jungle trekking routes during this time?

Good day,
I am trying to source train tickets for Tuesday 1 January from Chiang Mai to Phitsanulok. I have tried 1,2 GoAsia with no luck. Am trying to see if there are any other means I get train tickets? Yes I do know it is the holiday period and things are booked up but really desperate.....any help in advance would be appreciated. Thanks Karen

Save your time in Bangkok until the end of your trip. Two visits is a waste of time with a tight itinerary. Start in Ayutthaya, head north via wherever you fancy, and fly from Chiang mai to Krabi/Phuket for time on Koh Lanta. Khao sok could be squeezed in on the way back to Bangkok. 3 days in Bangkok should be enough.

Ok so for now it would be:
Day 1 to 4 Bangkok
Day 5 Ayyutthaya
Day 6-9 Chiang Mai
Day 10-13 Koh Lanta
Day 14 back to Bangkok
Day 15 fly home
Is it better to stay in Koh Lanta or maybe go to one of the island (or few) or just do the day trips around and use Lanta as starting point?
Yes I am planing to book everything ASAP that's why I am asking :).
But this pollution event is no snapshot, I assure you.
Not what I meant - the snapshot is that at one (or several) point(s) the air pollution during the several week long burning season in and around Chiang Mai surpasses that of other 'most polluted' cities in the world, and that this moment is used by the press to declare it the 'world's most polluted' city in their headline, which is rather bad journalism, just aimed to get more clicks.
As bad as Chiang Mai is during this period lasting over a month it's nowhere near the overall pollution levels of Delhi, for example.
Of course this doesn't make things any better for Chiang Mai right now, hope you guys get some rain soon - parts of Bangkok saw thunderstorms last night with some rain.
Interesting is that Chiang Mai's overall air pollution levels during this time of the year is similar to the one in Bangkok end of January, when schools were closed for two days in the city.
The reason/mechanics of the pollution is much different in both places, however it is telling that the pollution has been on this level for more than a month now in Chiang Mai!
Next year the fields will be burned once more, and it will be the same all over again, with some yearly variation. As finding alternatives to burning seems difficult/more labour intensive/more expensive and it encompasses the entire area (not only Thailand) don't expect any fundamentally changes.
See you next year.
:-(