One of the great things about Myanmar (also known as Burma), is the fact that the weather patterns are relatively predictable. The region is known for having two to three (3) distinct seasons. While some limit the weather's seasons from wet to dry, those who are more weather sensitive break it down into the following:
The Cool Season - The end of October/November to February. The weather is dry and pleasantly warm, but not uncomfortably hot.
The Hot/Dry Season - From March to May, the climate is dry, but also capable of reaching temperatures up to 104℉ (40℃). Should you get a bit of rain, expect the weather to be noticeably muggy.
The Wet/Rainy Season - Late May/June to early October is when you can expect Myanmar to be at its windiest and wettest.
Peak Travel vs Off-Season
As you might expect, most tourists plan their Burmese getaway during the cool season. You will enjoy plenty of pleasant weather — along with the other tourists. If you go during the peak season you must anticipate that there will be a lot of other international travelers there too.
On the other hand, if you're hoping to soak up Burmese culture apart from the crowds, then consider booking your trip during the 'green season.' Green season is famous for being a travel double entendre — the rain is what keeps areas lush and green, but because it's not peak travel time, you can also save money (also known as 'green' in the United States) on tours and accommodations.
So long as you're not near some of the coastal areas at risk of being hit the hardest during the heart of the monsoon season, then visting Myanmar off-peak is a great way to explore the country away from crowds and enjoy more personalized attention on your tours and expeditions.
Bring at Least One...
Whenever you choose to go, it's recommended that you bring a cozy jacket made of fleece (or a comparable material) or your favorite warm sweater/jumper. Evening temperatures can noticeably dip, weather you're staying on the coast or in the foothills.