Getting an idea of what to expect from the weather in Lahan Sai will help you enjoy your stay to the fullest. The hottest months are usually April and March, with an average temperature of 29°C, while the coldest months are January and December, with an average of 25°C. The rainiest months in Lahan Sai are September, July, August and October, with each month seeing an average of 255 mm of rainfall.