Weather is probably a major factor when you plan your trip to São João del Rei, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually September and October with an average temp of 69°F, while the coldest months are July and August with an average of 62°F. The rainiest months in São João del Rei are December, January, November, and February, with each month seeing an average of 10 inches of rainfall.