Juiz de Fora's highland location gives it a more comfortable climate than coastal Brazil. At around 700 metres elevation, temperatures are moderate year-round: warm but rarely brutal in summer (December to March), and genuinely cool in winter (June to August), when locals don jackets for evening outings. Rain falls mainly in the summer months, and afternoon showers are common from November through March.
The best time to visit is during the shoulder seasons — April to June and August to October — when the weather is pleasant and the city goes about its normal life. The São João festivals in June are a highlight, with forró dancing and street food across the city. Avoid carnival week unless you specifically want to experience it: most of the city empties as residents head to the coast.