The Rio de Janeiro weather forecast is usually tropical and mild throughout the year. Although winter temperatures can get chilly and windy, Rio weather is still generally balmy throughout the year. Keep in mind that the seasons are the opposite from what they are in the Northern hemisphere, so summer begins in October, and winter begins in May.
Rio in summer (January through March): The peak of the summer season, Rio weather is quite hot, requiring air conditioners and multiple showers every day. Temperatures hover around 86 degrees Fahrenheit (30 Celsius), and the Carnival celebrations make this time of year a wonderful time to visit Rio. The weather stays balmy into March, but thunderstorms and showers may occur. They usually don't last long though, and sunny days continue to be the norm.
Rio in fall (April through June): Autumn begins to make its presence felt and you'll see the leaves changing color. The Rio de Janeiro weather forecast boasts comfortable warm weather, but in May, winter is clearly on its way and nighttime temperatures begin to drop. You may need a sweater to keep warm at night. Winter officially arrives in late June, and the dry season begins. It can get chilly and damp by the sea, so pack accordingly.
Rio in winter (July through September): Although July can be chilly, it's still a popular time for people on summer vacations from the Northern hemisphere. Beaches may not be as pleasant, but there are plenty of other things to see. In August, chilly days are sometimes interspersed with odd periods of warm weather. Count yourself lucky if one of these mini-summers coincide with your visit. In September, the spring weather arrives with clear skies perfect for views and far more comfortable temperatures than what you’ll find in the summer—this is a great time for hiking or other outdoor activities that don’t involve the beach.
Rio in summer (October through December): Temperatures begin to climb back to beach-friendly temperatures in October, and beginning in November, snowbirds from colder countries begin to flock to Rio for the warm sun and great beaches. Thousands of tourists come to Rio for the Christmas holidays, as December is a peak summer month, with average highs in the mid-80s and lows dipping only to the low 70s.