The cool season (November to February) is the best time to visit. Temperatures are comfortable (25–30°C during the day, cooler at night), humidity is manageable, and rainfall is minimal. This is peak tourist season and accommodation prices are highest.
The hot season (March to May) is oppressive — temperatures regularly exceed 40°C in April, and the humidity is brutal. Avoid if possible.
The monsoon (June to October) brings heavy daily rain and high humidity. The city continues to function normally, and there are fewer tourists, but the heat remains and flooding occurs in low-lying areas. The Shwedagon and other outdoor sights become muddy and streaming with water. If you come during the monsoon, a lightweight rain jacket is essential.
The Water Festival (Thingyan) in mid-April is Myanmar's new year celebration. The entire country essentially stops for a week of water-throwing festivities. Yangon's celebrations are among the most exuberant — expect to get soaked.