Rio is a year-round destination, but Carnival, which usually takes place in February, is the best time to soak up the city's energy. Arrive a few days before the celebrations begin, or stay a few days after they end to enjoy the museums and other sights that close for the four days of revelry. Prices rise substantially during Carnival season, and accommodations need to be booked several months in advance.
Temperatures in Rio tend to be the highest from January to March, when they often soar above 100 degrees. The city generally sees the most rain during December, when it might pour for days at a time. To tour the city at a quieter time with gentler temperatures and at lower prices, come in the off-season, from May to October (Brazil's winter). The temperature in the winter tends to be in the upper 70s during the day and rarely falls below 50 degrees at night.