If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Bertioga: The hottest months are usually February and January, with an average temperature of 25°C, while the coldest months are July and August, with an average of 20°C. The rainiest months in Bertioga are January, February, March and December, with each month seeing an average of 306 mm of rainfall.