Taking into account the local weather in Sibu Island is an important factor for planning your visit, especially if you plan to spend your trip poolside. The hottest months are usually May and June with an average temp of 82°F, while the coldest months are January and February with an average of 79°F. The rainiest months in Sibu Island are December, November, January, and October, with each month seeing an average of 15 inches of rainfall.