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December Weather in Riley, United States

Last updated: June 24, 2025

In December, the average temperature in Riley, United States hovers around 3°C (37°F), with a remarkable temperature range that can dip to a minimum of -17°C (1°F) and reach a maximum of 24°C (75°F). Expect an average precipitation of 27 mm (1.0 in) spread over 3 days, contributing to a high average humidity of 84%. Stay prepared for the climate's surprising twists!

December Temperature in Riley

In December in Riley, the average temperature is 3°C (37°F), with maximums reaching up to 24°C (75°F) and minimums dropping as low as -17°C (1°F). Travelers should be prepared for a wide range of temperatures, ensuring they bring appropriate clothing for both warm and cold conditions.

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

The chart illustrates December temperature patterns in Riley, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Riley, December typically has an average temperature of 3°C (37°F), with highs reaching up to 24°C (75°F) and lows dropping to around -17°C (1°F).
JanFebMarAprMayJunJulAugSepOctNovDec313246546678817773574437
Data source: Temperature data for Riley 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 Riley

In Riley in December, the precipitation amount is 27 mm (1.0 in) over the course of 3 days.

December Precipitation Trends in Riley

The chart displays monthly precipitation patterns in Riley, 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 Riley, December typically receives around 27 mm (1.0 inches) of precipitation spread over approximately 3 days.
JanFebMarAprMayJunJulAugSepOctNovDec30288467185798011964983327
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Riley

In Riley in December humidity is 84%. With an average temperature of 3°C (37°F), this humidity feels like a damp chill that seeps into your bones, making outdoor excursions brisk and invigorating, yet requiring extra layers to stay comfortable.

December Average Humidity in Riley

This chart illustrates the average monthly humidity levels in Riley, 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 Riley is approximately 84%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%78%70%73%82%82%81%78%71%71%81%84%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Riley

In Riley in December, the maximum UV index is 3, which corresponds to a moderate Exposure Category. The time to burn is approximately 30 minutes. For more details on the hourly UV index in Riley, you can check the information here.

Maximum UV Index Levels in Riley for December

The chart shows the monthly maximum UV Index (UVI) for Riley 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 Riley typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3569101111109643
Data source: Riley 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 Riley Compares to Other Months

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

This table compares monthly weather conditions in Riley, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-1°C (31°F)30 mm (1.2 inches)76%moderate
February Weather0°C (32°F)28 mm (1.1 inches)77%moderate
March Weather8°C (46°F)84 mm (3.3 inches)70%high
April Weather12°C (55°F)67 mm (2.6 inches)73%very high
May Weather19°C (66°F)185 mm (7.3 inches)82%very high
June Weather26°C (79°F)79 mm (3.1 inches)82%extreme
July Weather27°C (81°F)80 mm (3.1 inches)81%extreme
August Weather25°C (78°F)119 mm (4.7 inches)78%very high
September Weather23°C (73°F)64 mm (2.5 inches)71%very high
October Weather14°C (57°F)98 mm (3.9 inches)71%high
November Weather7°C (44°F)33 mm (1.3 inches)81%moderate
December Weather3°C (37°F)27 mm (1.0 inches)84%moderate

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