Nova Friburgo has a highland subtropical climate that is noticeably cooler than Rio de Janeiro year-round. Temperatures rarely exceed 28°C in summer (November to March) and can drop to near freezing on winter nights (June to August), which for Brazilians from the coast is a dramatic and welcome novelty. The mountain evenings almost always require a jacket.
The rainy season runs from November to March, when afternoon thunderstorms are common and the surrounding peaks can cloud in quickly. Hiking is still possible but trails get muddy and rivers run fast — local advice on river levels matters before a rafting trip in Lumiar. The dry winter months of June to August are the most comfortable for outdoor activity and the most popular with Brazilian tourists. July in particular is busy: school holidays and the appeal of cooler weather bring visitors from across the state.