If you're hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Bagan: The hottest months are usually April and May, with an average temperature of 31°C, while the coldest months are January and December, with an average of 24°C. The rainiest months in Bagan are September, August, October and July, with each month seeing an average of 176 mm of rainfall.