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December Weather in Philadelphia, United States

Last updated: June 24, 2025

In December, the average temperature in Philadelphia, United States hovers around 10°C (51°F). Expect a chill with minimums dropping to -6°C (21°F), while the mercury can rise to a pleasant 26°C (79°F). Prepare for some rainfall, as the area receives an average of 121 mm (4.8 in) over 12 days, all accompanied by a high humidity level of 88%.

December Temperature in Philadelphia

In December in Philadelphia, the average temperature is 10°C (51°F). Maximum can reach 26°C (79°F), and minimum can be as low as -6°C (21°F). Travelers should be prepared for a wide range of temperatures, making layering essential for comfort during their visit.

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

The chart illustrates December temperature patterns in Philadelphia, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Philadelphia, December typically has an average temperature of 10°C (51°F), with highs reaching up to 26°C (79°F) and lows dropping to around -6°C (21°F).
JanFebMarAprMayJunJulAugSepOctNovDec485360647378818077685451
Data source: Temperature data for Philadelphia 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 Philadelphia

In Philadelphia in December, the precipitation amount reaches 121 mm (4.8 in) over the course of 12 days.

December Precipitation Trends in Philadelphia

The chart displays monthly precipitation patterns in Philadelphia, 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 Philadelphia, December typically receives around 121 mm (4.8 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec1101731221581291681071309310668121
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Philadelphia

In Philadelphia in December, humidity is 88%. With an average temperature of 10°C (51°F), this humidity feels like a thick blanket of moisture enveloping you, making every step feel heavier and leaving you yearning for a refreshing breeze as you navigate the streets.

December Average Humidity in Philadelphia

This chart illustrates the average monthly humidity levels in Philadelphia, 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 Philadelphia is approximately 88%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%84%82%82%82%79%82%77%74%73%85%88%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Philadelphia

In Philadelphia 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 Philadelphia for better planning.

Maximum UV Index Levels in Philadelphia for December

The chart shows the monthly maximum UV Index (UVI) for Philadelphia 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 Philadelphia typically reaches 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec47810111111119864
Data source: Philadelphia 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 Philadelphia Compares to Other Months

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

This table compares monthly weather conditions in Philadelphia, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather9°C (48°F)110 mm (4.3 inches)85%moderate
February Weather11°C (53°F)173 mm (6.8 inches)84%high
March Weather15°C (60°F)121 mm (4.8 inches)82%very high
April Weather18°C (64°F)158 mm (6.2 inches)82%very high
May Weather23°C (73°F)129 mm (5.1 inches)82%extreme
June Weather26°C (79°F)168 mm (6.6 inches)79%extreme
July Weather27°C (81°F)107 mm (4.2 inches)82%extreme
August Weather27°C (80°F)130 mm (5.1 inches)77%extreme
September Weather25°C (77°F)93 mm (3.7 inches)74%very high
October Weather20°C (68°F)106 mm (4.2 inches)73%very high
November Weather12°C (54°F)68 mm (2.7 inches)85%high
December Weather10°C (51°F)121 mm (4.8 inches)88%moderate

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