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December Weather in New Castle, United States

Last updated: June 24, 2025

In New Castle, United States, the average temperature for December hovers around -6°C (22°F). However, temperatures can swing dramatically, with minimums plunging to -29°C (-21°F) and maximums peaking at 12°C (55°F). Expect 55 mm (2.2 in) of precipitation over 10 days, and brace yourself for a high average humidity of 90%.

December Temperature in New Castle

In December in New Castle, the average temperature is -6°C (22°F). The maximum can reach 12°C (55°F), while the minimum can drop as low as -29°C (-21°F). Travelers should be prepared for a wide range of temperatures and dress in layers to stay comfortable.

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 -6°C (22°F), with highs reaching up to 12°C (55°F) and lows dropping to around -29°C (-21°F).
JanFebMarAprMayJunJulAugSepOctNovDec212533395063706860433121
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 55 mm (2.2 in) spread over a duration 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 55 mm (2.2 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec557361484418131318604055
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 90%. With an average temperature of -6°C (22°F), this humidity feels like a biting chill that seeps into your bones, making travel uncomfortable and necessitating extra layers to stay warm while navigating through the damp, frosty air.

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 90%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec90%89%81%74%58%47%39%39%53%72%84%90%
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 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 New Castle for better planning.

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 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec469121213121210754
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 Weather-6°C (22°F)55 mm (2.2 inches)90%moderate
February Weather-4°C (25°F)73 mm (2.9 inches)89%high
March Weather1°C (33°F)61 mm (2.4 inches)81%very high
April Weather4°C (39°F)48 mm (1.9 inches)74%extreme
May Weather10°C (50°F)43 mm (1.7 inches)58%extreme
June Weather17°C (63°F)18 mm (0.7 inches)47%extreme
July Weather21°C (70°F)13 mm (0.5 inches)39%extreme
August Weather20°C (68°F)13 mm (0.5 inches)39%extreme
September Weather16°C (60°F)18 mm (0.7 inches)53%very high
October Weather6°C (43°F)60 mm (2.4 inches)72%high
November Weather0°C (32°F)39 mm (1.6 inches)84%moderate
December Weather-6°C (22°F)55 mm (2.2 inches)90%moderate

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