Weather is probably a major factor when you plan your trip to Khong Island, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually March and April with an average temp of 87°F, while the coldest months are January and December with an average of 81°F. The rainiest months in Khong Island are August, September, July, and June, with each month seeing an average of 16 inches of rainfall.