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December Weather in Chantilly, United States

Last updated: June 24, 2025

In December, the average temperature in Chantilly, United States hovers around 4°C (40°F). Expect a chilly minimum of -11°C (12°F) and a pleasant maximum of 20°C (68°F). You'll encounter 92 mm (3.6 in) of precipitation over approximately 9 days, with humidity levels averaging a brisk 85%. Stay warm and prepared for the varying weather!

December Temperature in Chantilly

In December in Chantilly, the average temperature is 4°C (40°F). Maximum temperatures can reach 20°C (68°F), while minimums can drop to as low as -11°C (12°F). Be prepared for a mix of mild and chilly weather, making it essential to pack layers for your trip.

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

The chart illustrates December temperature patterns in Chantilly, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Chantilly, December typically has an average temperature of 4°C (40°F), with highs reaching up to 20°C (68°F) and lows dropping to around -11°C (12°F).
JanFebMarAprMayJunJulAugSepOctNovDec364046566675807771614640
Data source: Temperature data for Chantilly 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 Chantilly

In Chantilly in December, the precipitation amount is 92 mm (3.6 in) during 9 days, indicating a relatively wet period for the region.

December Precipitation Trends in Chantilly

The chart displays monthly precipitation patterns in Chantilly, 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 Chantilly, December typically receives around 92 mm (3.6 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec5997831001311101261371021058792
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Chantilly

In Chantilly in December, humidity is 85%. With an average temperature of 4°C (40°F), this humidity feels like an icy blanket wrapping around you, making outdoor activities feel much colder and damp, which can be quite uncomfortable for traveling.

December Average Humidity in Chantilly

This chart illustrates the average monthly humidity levels in Chantilly, 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 Chantilly is approximately 85%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%86%86%84%78%79%70%59%68%80%87%85%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Chantilly

In Chantilly 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 Chantilly, you can check the information here.

Maximum UV Index Levels in Chantilly for December

The chart shows the monthly maximum UV Index (UVI) for Chantilly 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 Chantilly typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec357910101098753
Data source: Chantilly 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 Chantilly Compares to Other Months

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

This table compares monthly weather conditions in Chantilly, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather2°C (36°F)59 mm (2.3 inches)86%moderate
February Weather5°C (41°F)97 mm (3.8 inches)86%moderate
March Weather8°C (46°F)83 mm (3.3 inches)86%high
April Weather13°C (56°F)100 mm (3.9 inches)84%very high
May Weather19°C (66°F)131 mm (5.2 inches)78%very high
June Weather24°C (75°F)110 mm (4.3 inches)79%very high
July Weather27°C (80°F)126 mm (5.0 inches)70%very high
August Weather25°C (77°F)137 mm (5.4 inches)59%very high
September Weather22°C (71°F)102 mm (4.0 inches)68%very high
October Weather16°C (62°F)105 mm (4.1 inches)80%high
November Weather8°C (47°F)87 mm (3.4 inches)86%moderate
December Weather4°C (40°F)92 mm (3.6 inches)85%moderate

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