Planning for the weather is a good way to make your trip to Blumenau relaxing and enjoyable, especially when you're splurging. The hottest months are usually January and February with an average temp of 74°F, while the coldest months are July and June with an average of 62°F. The rainiest months in Blumenau are January, February, March, and December, with each month seeing an average of 8 inches of rainfall.