Weather in Thailand in June
Hot and wet or hot and dry?
June arrives and it feels like the wet season has had a false start. In most of Thailand the level of rainfall drops a little (except for Ko Chang where it increases a lot). Temperatures stay around the same or fall slightly. As far as islands go, Ko Samui, Ko Pha Ngan and Ko Tao are your best bet. They'll still see some rain, but are about the driest of a pretty wet lot.
Bangkok and Central Thailand
June in Bangkok and Central Thailand is pretty much like May with half the rain. You'll still see rain every other day, but, especially in the countryside, the rain starts to bring out some of the beauty. Waterfalls in Kanchanaburi will pick up strength and sites like Ayutthaya will begin to get some of their green back.
June marks the beginning of a three month period when it pretty much pelts down on Ko Chang — not all day for sure, but almost every day. This is perfect if you want to avoid crowds or traipse around in the jungle hunting leeches (they'll find you), less so if you want to sunbake and snorkel. Avoiding the crowds can be a good thing though, and accommodation prices certainly will start to fall, but you'd need to be very lucky to score a weeklong dry period in June on Ko Chang.
Temperatures continues to slowly decline and you've got half the rain of last month, but that is still quite a bit. Trekking will involve mud, leeches and wetness, so pack a poncho. Rain every other day. On the upside the rivers will be picking up, making rafting out of spots like Pai more fun. Simultaneously the jungle will continue its transition from parched wilderness to lush jungle. "Good the photos, bad for leeches" forms our Northern Thailand June weather report.
As with the rest of Thailand, a continued downward slide in daily average temperatures and less rainfall than the previous month. Mekong riverfront towns like Nong Khai, Sangkhom and That Phanom can be pretty this time of the year as the Mekong's waters will be picking up and they'll be a little more boat traffic to watch. Overall this isn't a bad time to visit the northeast.
While there is still rain, Ko Samui and surrounds is about your best bet for beach time in June. Samui, Ko Pha Ngan and Ko Tao are all reasonably good and certainly will have better weather than pretty much anything on the west coast or up around Ko Chang. So if it is island time you are after, this is the region where you should head to.
May and June are really not all that different on the Andaman coast. The rain level is about the same (roughly every other day) and the temperature slips only slightly. The seas pick up though and some ferries — notably those out to Ko Lipe run on a far less regular timetable. As with May, keep an eye out for discounted hotels in the big resort areas. On some of the quieter islands like Ko Jum and Ko Lanta some of the smaller guesthouses may shut down or run with just a skeleton staff.