Last updated: June 24, 2025
In September, the average temperature in Rio, United States hovers around 18°C (65°F), with fluctuations that can range from a cool 2°C (35°F) to a warm 33°C (92°F). Expect about 98 mm (3.8 in) of precipitation over 10 days and a comfortable average humidity of 79%.
In September in Rio, the average temperature is 18°C (65°F). The maximum can reach 33°C (92°F), while the minimum can drop as low as 2°C (35°F). This diverse climate makes Rio a great destination for travelers seeking both warmth and cool, refreshing conditions.
In Rio in September, the precipitation amount is 98 mm (3.8 in) spread over a period of 10 days.
In Rio in September, humidity is 79%. With an average temperature of 18°C (65°F), this humidity feels like walking through a warm mist, making traveling slightly uncomfortable and sticky, but offering a refreshing escape when you find moments of shade or a breeze.
In Rio in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Rio.
UV Risk Categories
Weather in Rio varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Rio, focusing on differences in temperature, rainfall, humidity, and UV levels.
Temperature | Precipitation | Humidity | UV | |
---|---|---|---|---|
January Weather | -6°C (21°F) | 47 mm (1.9 inches) | 85% | moderate |
February Weather | -6°C (21°F) | 52 mm (2.0 inches) | 85% | moderate |
March Weather | 2°C (35°F) | 58 mm (2.3 inches) | 85% | moderate |
April Weather | 7°C (45°F) | 98 mm (3.9 inches) | 85% | very high |
May Weather | 15°C (59°F) | 127 mm (5.0 inches) | 78% | very high |
June Weather | 21°C (70°F) | 112 mm (4.4 inches) | 80% | very high |
July Weather | 23°C (74°F) | 103 mm (4.1 inches) | 78% | very high |
August Weather | 22°C (71°F) | 100 mm (3.9 inches) | 76% | very high |
September Weather | 18°C (65°F) | 98 mm (3.8 inches) | 79% | high |
October Weather | 10°C (51°F) | 113 mm (4.5 inches) | 83% | moderate |
November Weather | 2°C (36°F) | 44 mm (1.7 inches) | 88% | moderate |
December Weather | -2°C (28°F) | 46 mm (1.8 inches) | 81% | low |