Weather in Thailand in March
Hot and wet or hot and dry?
March is the precursor to Thailand's hottest period. The numbers drop off as the mercury climbs. The throngs head south to the islands where the water offers an easy escape from the heat. You're also far from the eye-burning haze that begins to blight the north as the farmers burn their fields back in preparation for a new planting season.
Bangkok and Central Thailand
The mercury continues to climb through March. Expect mid 20s to mid-30s in both Bangkok and Central Thailand. The heat can be oppressive during the day, to the point where sightseeing becomes downright unpleasant. If you're sensitive to the heat be sure to grab an air-con room when available — you'll need it. Raindrops remain few and far between.
The rains start to hit the East of Thailand earlier than elsewhere. While far off the peak of the monsoon, don't be surprised if you see some rain every three or four days. The more frequent rain helps to keep the heat tapped down a little and it is certainly cooler here than in the blistering Northeast. If you want some island time but are bothered by the chance of rain, Ko Samet, roughly halfway between Bangkok and Ko Chang is a good compromise that sees little rain.
Daytime temperatures can hit the mid 30s in northern Thailand in March, but what is far more problematic than it just being bloody hot, is the haze. Every year in March Thai farmers burn back the stubble in their fields in preparation for the new planting season. This widespread burning (it happens all over the country but is especially bad in the north and northeast) creates a terrible haze that not only plays havoc with photos, also stings eyes and can cause respiratory problems. This really takes away from the northern Thailand experience and if possible you're best to avoid this region in March (and April for that matter). That there is very little rain only makes the haze all the worse.
As with the far north of Thailand, Northeast Thailand in March sees a heavy haze caused by farmers burning back their fields — it isn't as bad as in the north of the country, but it is still present nevertheless. Temperatures continue to rise, with mid 20s to mid 30s being the norm. The only real advantage to travelling in the northeast in March is that you can take comfort in knowing that it is even hotter in April!
Glorious weather on the Southeast coast and islands. Except (relatively) moderate temperatures from the mid 20s to low 30s and little rain. Ko Samui, Ko Pha Ngan and Ko Tao are all in excellent form in March.
In comparison to the east coast, Thailand's west coast in March sees hotter weather with a little bit more rain than what they're seeing on the Southeast coast. That isn't saying much though as there is little rain over there anyway this time of year. From Krabi to Ko Lanta and beyond, expect excellent weather and lower crowds that what were around in January and February. The temperature sits around the mid 20s to mid 30s range — perfect.