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 Itanhaem: 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 Itanhaem are January, February, March and December, with each month seeing an average of 278 mm of rainfall.