Plan your trip to the beach with a look at the seasons in Phumĭ Thmei: The hottest months are usually March and April, with an average temperature of 30°C, while the coldest months are December and January, with an average of 27°C. The rainiest months in Phumĭ Thmei are October, September, August and July, with each month seeing an average of 205 mm of rainfall.