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December Weather in McLean, United States

Last updated: June 24, 2025

In McLean, United States, the average temperature in December hovers around 6°C (42°F), with extremes ranging from a chilly -10°C (14°F) to a warm 26°C (80°F). Expect about 23 mm (0.9 in) of precipitation over 2 days, creating a refreshing atmosphere. The average humidity stands at a robust 81%, adding to the region's unique climate experience.

December Temperature in McLean

In December in McLean, the average temperature is 6°C (42°F). Maximum can reach 26°C (80°F) and minimum can be as low as -10°C (14°F). Travelers should be prepared for a wide range of temperatures, so layering clothing is recommended for comfort during their visit.

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

The chart illustrates December temperature patterns in McLean, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In McLean, December typically has an average temperature of 6°C (42°F), with highs reaching up to 26°C (80°F) and lows dropping to around -10°C (14°F).
JanFebMarAprMayJunJulAugSepOctNovDec383951576877817973594842
Data source: Temperature data for McLean 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 McLean

In McLean in December, the precipitation amount is 23 mm (0.9 in) over a span of 2 days.

December Precipitation Trends in McLean

The chart displays monthly precipitation patterns in McLean, 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 McLean, December typically receives around 23 mm (0.9 inches) of precipitation spread over approximately 2 days.
JanFebMarAprMayJunJulAugSepOctNovDec231559368259364350691423
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in McLean

In McLean in December humidity is 81%. With an average temperature of 6°C (42°F), this humidity feels like a chilly, damp embrace that can make outdoor activities uncomfortable and somewhat drizzling, leaving travelers yearning for warmer, dryer conditions.

December Average Humidity in McLean

This chart illustrates the average monthly humidity levels in McLean, 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 McLean is approximately 81%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec75%76%64%70%78%81%82%78%72%73%81%81%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in McLean

In McLean in December, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in McLean for better planning.

Maximum UV Index Levels in McLean for December

The chart shows the monthly maximum UV Index (UVI) for McLean 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 McLean typically reaches 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec468101112121110754
Data source: McLean 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 McLean Compares to Other Months

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

This table compares monthly weather conditions in McLean, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather3°C (38°F)23 mm (0.9 inches)75%moderate
February Weather4°C (39°F)15 mm (0.6 inches)76%high
March Weather11°C (51°F)59 mm (2.3 inches)64%very high
April Weather14°C (58°F)36 mm (1.4 inches)70%very high
May Weather20°C (68°F)82 mm (3.2 inches)78%extreme
June Weather25°C (77°F)59 mm (2.3 inches)81%extreme
July Weather27°C (81°F)36 mm (1.4 inches)82%extreme
August Weather26°C (79°F)43 mm (1.7 inches)78%extreme
September Weather23°C (73°F)50 mm (2.0 inches)72%very high
October Weather15°C (59°F)69 mm (2.7 inches)73%high
November Weather9°C (49°F)14 mm (0.5 inches)80%moderate
December Weather6°C (42°F)23 mm (0.9 inches)81%moderate

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