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December Weather in Rio, United States

Last updated: August 27, 2025

In December, the average temperature in Rio, United States hovers around -2°C (28°F). Expect a chilling minimum of -23°C (-8°F), while the warmest days can reach up to 18°C (65°F). Additionally, precipitation averages 46 mm (1.8 in) over 6 days, contributing to an average humidity of 81%. Stay prepared for a mix of frosty and mild conditions!

December Temperature in Rio

In December in Rio, the average temperature is -2°C (28°F). The maximum can reach 18°C (65°F) and the minimum can be as low as -23°C (-8°F). Travelers should be prepared for a wide range of temperatures when visiting during this time.

December Weather in Rio: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Rio, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Rio, December typically has an average temperature of -2°C (28°F), with highs reaching up to 18°C (65°F) and lows dropping to around -23°C (-8°F).
JanFebMarAprMayJunJulAugSepOctNovDec212135455970747164513628
Data source: Temperature data for Rio generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in Rio

In Rio in December, the precipitation amount is 46 mm (1.8 in) over a span of 6 days.

December Precipitation Trends in Rio

The chart displays monthly precipitation patterns in Rio, with values for each month alongside December’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how December’s conditions compare to those of other months. In Rio, December typically receives around 46 mm (1.8 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec47525898127112103100981134446
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Rio

In Rio in December, humidity is 81%. With an average temperature of -2°C (28°F), this humidity feels like a biting chill that seeps into your bones, making travel uncomfortable and necessitating extra layers to stay warm and dry.

December Average Humidity in Rio

This chart illustrates the average monthly humidity levels in Rio, with December’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In December, average humidity in Rio is approximately 81%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%85%85%85%78%80%78%76%79%83%88%82%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Rio

In Rio in December, the maximum UV index is 2, which corresponds to a low exposure category. With this level of UV radiation, the time to burn is approximately 45 minutes. To learn more about the hourly UV index in Rio, you can visit Hourly UV Index in Rio.

Maximum UV Index Levels in Rio for December

The chart shows the monthly maximum UV Index (UVI) for Rio in December, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In December, the maximum UV index in Rio typically reaches 2, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34589101097532
Data source: Rio December UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How December Weather in Rio Compares to Other Months

Weather in Rio varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Rio, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Rio, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
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 Weather2°C (35°F)58 mm (2.3 inches)85%moderate
April Weather7°C (45°F)98 mm (3.9 inches)85%very high
May Weather15°C (59°F)127 mm (5.0 inches)78%very high
June Weather21°C (70°F)112 mm (4.4 inches)80%very high
July Weather23°C (74°F)103 mm (4.1 inches)78%very high
August Weather22°C (71°F)100 mm (3.9 inches)76%very high
September Weather18°C (65°F)98 mm (3.8 inches)79%high
October Weather10°C (51°F)113 mm (4.5 inches)83%moderate
November Weather2°C (36°F)44 mm (1.7 inches)88%moderate
December Weather-2°C (28°F)46 mm (1.8 inches)81%low

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