Planning for the weather is a good way to make your trip to Itatiaia relaxing and enjoyable, especially when you’re splurging. The hottest months are usually February and January with an average temp of 72°F, while the coldest months are July and August with an average of 63°F. The rainiest months in Itatiaia are January, December, March, and February, with each month seeing an average of 10 inches of rainfall.