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December Weather in New Castle, United States

Last updated: June 24, 2025

In December, the average temperature in New Castle, United States hovers around 5°C (40°F), with fluctuations that can see it drop as low as -15°C (6°F) or rise to a pleasant 21°C (70°F). Expect 111 mm (4.4 in) of precipitation spread over 10 days, while the air remains relatively humid at an average of 87%. Enjoy the diverse weather as you explore this captivating destination!

December Temperature in New Castle

In December in New Castle, the average temperature is 5°C (40°F). Maximum temperatures can reach 21°C (70°F), while minimums can drop as low as -15°C (6°F). Be prepared for a wide range of temperatures, making it essential to pack layers for your travels.

December Weather in New Castle: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in New Castle, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In New Castle, December typically has an average temperature of 5°C (40°F), with highs reaching up to 21°C (70°F) and lows dropping to around -15°C (6°F).
JanFebMarAprMayJunJulAugSepOctNovDec353947556774787571604540
Data source: Temperature data for New Castle 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 New Castle

In New Castle in December, the precipitation amount is 111 mm (4.4 in) over a span of 10 days.

December Precipitation Trends in New Castle

The chart displays monthly precipitation patterns in New Castle, 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 New Castle, December typically receives around 111 mm (4.4 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec871291391431261591039911510692111
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in New Castle

In New Castle in December, humidity is 87%. With an average temperature of 5°C (40°F), this humidity feels like a damp chill that wraps around you, making outdoor excursions less enjoyable and requiring extra layers to stay comfortable while exploring.

December Average Humidity in New Castle

This chart illustrates the average monthly humidity levels in New Castle, 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 New Castle is approximately 87%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%85%86%84%79%82%79%70%69%76%88%87%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in New Castle

In New Castle 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 New Castle, you can check the information here.

Maximum UV Index Levels in New Castle for December

The chart shows the monthly maximum UV Index (UVI) for New Castle 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 New Castle typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3579101010108743
Data source: New Castle 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 New Castle Compares to Other Months

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

This table compares monthly weather conditions in New Castle, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (35°F)87 mm (3.4 inches)87%moderate
February Weather4°C (39°F)129 mm (5.1 inches)85%moderate
March Weather8°C (47°F)139 mm (5.5 inches)86%high
April Weather13°C (56°F)143 mm (5.6 inches)84%very high
May Weather19°C (67°F)126 mm (5.0 inches)79%very high
June Weather23°C (74°F)159 mm (6.3 inches)82%very high
July Weather25°C (78°F)103 mm (4.0 inches)79%very high
August Weather24°C (76°F)99 mm (3.9 inches)70%very high
September Weather22°C (71°F)115 mm (4.5 inches)69%very high
October Weather15°C (60°F)106 mm (4.2 inches)76%high
November Weather7°C (45°F)92 mm (3.6 inches)88%moderate
December Weather5°C (40°F)111 mm (4.4 inches)87%moderate

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