If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Tambunan: The hottest months are usually April and May with an average temp of 73°F, while the coldest months are February and January with an average of 72°F. The rainiest months in Tambunan are May, November, December, and October, with each month seeing an average of 18 inches of rainfall.