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 Itatiaia: The hottest months are usually February and January, with an average temperature of 22°C, while the coldest months are July and August, with an average of 17°C. The rainiest months in Itatiaia are January, December, March and February, with each month seeing an average of 255 mm of rainfall.