Rio has a typical tropical climate, so expect some rain and humidity. Summer (December to March) is hot, with temperatures ranging from 25°C (77°F) to a scorching 40°C (104°F). It can also be dreadfully muggy; there are more showers in summer than at other times, but they rarely last long. Winter temperatures range from around 20°C (68°F) to 30°C (86°F), with plenty of good beach days.
| Month | Temp (°C) | Rainfall (mm) | Humidity (%) | Sunshine (hours) |
| Jan | 23 - 29 | 125 | 7 | |
| Feb | 23 - 29 | 122 | 7 | |
| Mar | 22 - 28 | 130 | 7 | |
| Apr | 21 - 27 | 107 | 6 | |
| May | 19 - 25 | 79 | 6 | |
| Jun | 18 - 24 | 53 | 6 | |
| Jul | 17 - 24 | 41 | 6 | |
| Aug | 18 - 24 | 43 | 7 | |
| Sep | 18 - 24 | 66 | 5 | |
| Oct | 19 - 25 | 79 | 5 | |
| Nov | 20 - 26 | 104 | 6 | |
| Dec | 22 - 28 | 137 | 6 |