If you're looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Biak: The hottest months are usually October and May, with an average temperature of 28°C, while the coldest months are July and August, with an average of 27°C. The rainiest months in Biak are March, June, July and April, with each month seeing an average of 400 mm of rainfall.