Weather is probably a major factor when you plan your trip to Passo Fundo, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually January and December with an average temp of 70°F, while the coldest months are July and June with an average of 56°F. The rainiest months in Passo Fundo are October, May, September, and December, with each month seeing an average of 8 inches of rainfall.