If you’re hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Tambunan: The hottest months are usually April and May, with an average temperature of 23°C, while the coldest months are February and January, with an average of 22°C. The rainiest months in Tambunan are May, November, December and October, with each month seeing an average of 447 mm of rainfall.