Weather will likely play an important role when you plan your trip to Khaem Son, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually April and March with an average temp of 82°F, while the coldest months are December and January with an average of 76°F. The rainiest months in Khaem Son are August, July, May, and September, with each month seeing an average of 18 inches of rainfall.