Weather is probably a major factor when you plan your trip to Sibu, 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 Sibu are December, January, November, and October, with each month seeing an average of 13 inches of rainfall.