Weather is probably a major factor when you plan your trip to Simunjan, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually May and August with an average temp of 80°F, while the coldest months are February and March with an average of 78°F. The rainiest months in Simunjan are January, December, November, and February, with each month seeing an average of 15 inches of rainfall.