December Weather in Philadelphia, United States

Last updated: February 24, 2025

In December, Philadelphia experiences a notable shift in weather, characterized by a maximum temperature reaching 19°C (67°F) and an average low of only 4°C (40°F), with the mercury occasionally dipping to a brisk -12°C (10°F). The month is also marked by a relatively high humidity level of 84%, creating a chill in the air. Despite the cold, the city sees approximately 100 mm (4.0 in) of precipitation over about 10 days, resulting in a mix of rain and the possibility of early winter snow. This combination of temperatures and precipitation defines the unique, wintry charm of Philadelphia during the festive season.

December Temperature in Philadelphia

In Philadelphia, December ushers in a wintry chill, with temperatures typically ranging from a brisk -12°C (10°F) overnight low to a mild daytime high of 19°C (67°F). The average temperature settles around 4°C (40°F), marking a notable dip from the more moderate fall months. As the year draws to a close, these temperatures highlight the transition into winter, with frosty mornings becoming commonplace. Interestingly, December’s max temperatures are still relatively pleasant compared to the depths of winter in January and February, suggesting a gradual shift before the colder peaks of the season. Overall, December in Philadelphia brings a crisp air that invites cozy gatherings and festive cheer.

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.
JanFebMarAprMayJunJulAugSepOctNovDec353944546473797771614639
Data source: Temperature data for Philadelphia generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in Philadelphia

December in Philadelphia sees 100 mm (4.0 in) of precipitation, marking a noteworthy point in the city's weather pattern as the year draws to a close. With approximately 10 days of rainfall, December provides a steady stream of moisture that contributes to the winter landscape. This month sits comfortably between the wetter summer months, like July and August, which receive over 130 mm (5.2 in) each, and the drier fall months, such as November, where precipitation dips to just 83 mm (3.3 in). As the holiday season approaches, this balance of rain helps to refresh the city's ecosystem while also hinting at the more severe winter weather that often follows. Overall, December's precipitation not only underscores a slight seasonal decline but also maintains the rhythm of Philadelphia’s climatological year.

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.
JanFebMarAprMayJunJulAugSepOctNovDec631091071051331021311349310683100
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Philadelphia

As December settles in Philadelphia, the city experiences a notable return to elevated humidity levels, with an average of 84% for the month. This figure reflects a slight increase compared to the previous months, particularly November's high of 85%. Throughout the year, humidity trends showcase a gradual decline from a peak in the winter months, with figures hovering around 84% in January and February, and dipping to their lowest point in the sweltering summer, where July and August see a decrease to 74% and 72%, respectively. As autumn approaches, humidity rises again, hinting at the interplay between seasonal changes and moisture levels. December's humidity, therefore, serves as a reminder of the lingering winter influences, while still echoing the patterns of moisture retained throughout the fall. Overall, the consistency of higher humidity in late fall and early winter emphasizes Philadelphia's unique climate rhythm.

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, allowing you to see how December's humidity levels compare to other months.
JanFebMarAprMayJunJulAugSepOctNovDec84%83%83%81%78%79%74%72%75%81%85%84%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Philadelphia

In December, Philadelphia experiences a moderate UV Index of 3, similar to the beginning of the year, indicating it’s safe for most outdoor activities with a burn time of 30 minutes. As we look over the months, a clear trend emerges: from January through February, the UV levels remain at a moderate range, gradually intensifying mid-year. The peak comes in the summer months of May through July, where the index reaches a notable 10, signaling very high exposure, with just 15 minutes before skin damage can occur. As autumn fades, the UV Index gradually declines, returning to a moderate level by November and settling in this comfortable range in December. For a detailed look at UV trends throughout the year, check out Philadelphia UV Index.

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.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098643
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.

December Sunshine in Philadelphia

As December descends on Philadelphia, the city basks in a modest 179 hours of sunshine, a decline compared to the vibrant months leading up to it. Winter’s chill begins to set in, following a peak of 346 hours in July, the sunniest month of the year. This shift marks a noticeable transition from the sun-drenched days of summer, as the days grow shorter and cloud cover becomes more common. Interestingly, December’s sunshine also trails behind the fall months, which still enjoy considerable light, with September basking in 264 hours and October capturing 223 hours. Despite this, December’s sunlight offers a glimmer of hope, reminding us that even in the depths of winter, there are still moments of brightness to embrace.

Monthly Sunshine Duration in Philadelphia: December Highlighted

The December sunshine duration represents the total number of hours Philadelphia experiences direct sunlight during the month of December, excluding cloudy or obstructed periods. This chart compares the sunshine duration of December with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec144h174h245h246h273h311h346h309h264h223h221h179h
Data source: Philadelphia December Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Philadelphia During December

In Philadelphia, December brings a notable dip in sunny weather, with a 32% chance of sunshine. This trend reflects the city's seasonal shift, as earlier months like March and September enjoy significantly higher probabilities, reaching up to 55%. As temperatures drop towards winter, the likelihood of clear skies diminishes compared to the pre-winter months of November and October, which show higher chances at 55% and 38%, respectively. Ultimately, if you're dreaming of a bright and sunny December, it's best to manage your expectations and prepare for a more overcast month.

Percentage of Sunny Days in December in Philadelphia

The chart illustrates the percentage of sunny days in Philadelphia throughout the year, with December highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often Philadelphia experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec46%28%55%44%40%36%47%33%52%38%55%32%
Data source: Philadelphia December chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Philadelphia in December

In Philadelphia, the daylight duration exhibits a distinctive seasonal rhythm throughout the year. December marks the low point of this cycle, offering only 9 hours of daylight, mirroring the brevity characteristic of both January and November. As winter takes hold, the daylight gradually recedes from the summer peak of 14 hours in June and July. Following the festive season, illumination begins to slowly extend, with each month bringing incremental increases in daylight, culminating in April’s 13 hours—a precursor to the vibrant summer months. This trend showcases a natural ebb and flow, where each month gracefully ushers in a new phase of the sun’s presence, enriching Philadelphia’s seasonal experience.

Average Daylight Hours in Philadelphia for December

The chart illustrates the variation in daylight duration in Philadelphia throughout the year, with December highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 41m10h 41m11h 58m13h 17m14h 23m14h 56m14h 38m13h 39m12h 23m11h 5m9h 57m9h 22m
Data source: Philadelphia daylight hours, calculated by summing the hours between sunrise and sunset for each day.

December Winds in Philadelphia

As December rolls into Philadelphia, the city's winds take on a gentle, crisp character, with an average wind speed of 2.9 m/s (6 mph). This slight decline from November's 3.1 m/s reflects a consistent trend of diminishing wind speeds as the temperatures drop heading into winter. Compared to the spring months, which peak at 3.7 m/s in March, December's breezes evoke a calmer, serene atmosphere, perfect for cozy holiday strolls along the streets. Interestingly, the summer months showcase the lowest speeds, with 2.2 m/s in August, indicating a seasonal pattern that highlights the shift from lively summer gales to the more subdued winter winds. Overall, December's winds are a soft reminder that, while the chill sets in, the energy of the city continues to flow quietly beneath the surface.

Average December Wind Speed in Philadelphia

The chart displays monthly wind speed patterns in Philadelphia, with values for each month shown alongside December's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how December's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec3.33.53.73.53.12.72.32.23.03.03.12.9 m/s
Data source: Philadelphia December wind data, generated using information from the Copernicus Climate Change Service.

How December Weather in Philadelphia Compares to Other Months

The weather in Philadelphia changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of December's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in Philadelphia and find detailed weather information for every month.

In December, the weather in Philadelphia features a milder average temperature of 4°C (40°F), with highs reaching up to 19°C (67°F) and lows dropping to -12°C (10°F). The month experiences significant precipitation, totaling around 100 mm (4.0 in) over approximately 10 days, while humidity remains consistently high at 84%.

In contrast, January brings colder temperatures, with an average of 2°C (36°F) and slightly lower highs at 20°C (68°F), though it can drop to a minimum of -17°C (1°F). Precipitation decreases to about 63 mm (2.5 in) across 9 days, but humidity stays stable at 84%. For a more detailed look at January weather, check out Philadelphia weather in January.

December and February in Philadelphia showcase notable differences in temperature and precipitation patterns. In December, temperatures range from a minimum of -12°C (10°F) to a maximum of 19°C (67°F), with an average of 4°C (40°F). The month sees about 100 mm (4.0 in) of precipitation over 10 days and has a humidity level of 84%. In contrast, February experiences slightly colder minimum temperatures of -15°C (5°F), but a more significant maximum of 26°C (78°F) with the same average of 4°C (39°F). Precipitation in February increases slightly to 108 mm (4.3 in) over 11 days, while humidity remains similar at 83%. For a more detailed look into February's weather patterns, visit Philadelphia weather in February.

December and March showcase contrasting weather patterns, although both months experience relatively low temperatures. December sees a range from a chilly minimum of -12°C (10°F) to a maximum of 19°C (67°F), with an average temperature of 4°C (40°F) and high humidity at 84%. In contrast, March brings slightly milder conditions, with a minimum temperature of -11°C (12°F) and a maximum reaching 28°C (83°F), while the average temperature rises to 7°C (44°F). Both months receive comparable precipitation, with December at 100 mm (4.0 in) and March slightly higher at 107 mm (4.2 in), maintaining precipitation on about 10 days and a similar humidity level of 83%. For more detailed insights into March weather, visit Philadelphia weather in March.

In comparing the weather of December and April, one can observe notable differences in temperature and precipitation patterns. December experiences much colder temperatures, with a minimum of -12°C (10°F) and an average of 4°C (40°F), while April offers a milder climate, where minimum temperatures reach -2°C (29°F) and averages rise to 12°C (55°F). Although precipitation is similar—100 mm (4.0 in) in December and 105 mm (4.1 in) in April—the rainfall days are slightly greater in April, at 11 days compared to December's 10 days. Additionally, humidity remains relatively high in both months, but is marginally lower in April at 81% compared to December’s 84%. For more detailed insights into April weather, you can refer to Philadelphia weather in April.

December and May showcase stark contrasts in weather patterns. In December, temperatures can plummet as low as -12°C (10°F), with an average of 4°C (40°F) and highs reaching 19°C (67°F). This month also sees significant precipitation, totaling 100 mm (4.0 in) over about 10 days, and high humidity levels at 84%. In contrast, May brings much warmer conditions with a minimum temperature of 2°C (35°F), an average of 18°C (65°F), and maximums soaring to 35°C (95°F). While May experiences slightly more precipitation at 133 mm (5.2 in) spread over 14 days, the overall humidity is lower at 78%. For more detailed information, you can explore Philadelphia weather in May.

December and June present starkly contrasting weather conditions. In December, temperatures can plunge as low as -12°C (10°F), with an average around 4°C (40°F) and a maximum that reaches only 19°C (67°F). The month is marked by high humidity at 84% and about 100 mm (4.0 in) of precipitation spread over 10 days. In contrast, June boasts much warmer temperatures, with a minimum of 10°C (50°F), an average of 23°C (74°F), and peaks hitting 36°C (98°F). Despite a similar amount of precipitation at 102 mm (4.0 in) and 11 days of rain, June's humidity is slightly lower at 79%. For more details on this summer month, you can explore Philadelphia weather in June.

December and July present stark contrasts in weather conditions. In December, temperatures can plummet to a minimum of -12°C (10°F) while averaging around 4°C (40°F), perfect for cozy winter activities. Precipitation is notable, with about 100 mm (4.0 in) falling over 10 days, contributing to a relatively high humidity level of 84%. In contrast, July boasts warmer temperatures, with a minimum of 14°C (58°F) and an average of 26°C (79°F), peaking at a sizzling 37°C (99°F). Although July experiences slightly more precipitation at 131 mm (5.2 in) over 13 days, the humidity is lower at 74%. For a more detailed look at the summer climate, check out Philadelphia weather in July.

December and August present stark contrasts in weather. In December, temperatures can plummet to a minimum of -12°C (10°F), with an average of 4°C (40°F) and a max reaching 19°C (67°F). This month also experiences higher humidity at 84% and about 100 mm (4.0 in) of precipitation over 10 days. Conversely, August brings much warmer temperatures with a minimum of 14°C (58°F), an average of 25°C (77°F), and a maximum of 35°C (96°F). Rainfall increases slightly to 134 mm (5.3 in) over 14 days, but the humidity is lower at 72%. For more details on August weather, check out Philadelphia weather in August.

December and September present contrasting weather patterns. December, with temperatures ranging from a low of -12°C (10°F) to a high of 19°C (67°F), is significantly colder, featuring an average temperature of 4°C (40°F). In contrast, September boasts a much warmer climate with temperatures fluctuating between 6°C (44°F) and a peak of 35°C (95°F), averaging around 22°C (71°F). Precipitation levels are somewhat similar, with December receiving 100 mm (4.0 in) and September at 93 mm (3.7 in), both spread over approximately 10 days. Notably, December's higher humidity at 84% compared to September's 75% adds to the chill of the winter air. For more insights on September weather, you can view Philadelphia weather in September.

December weather is typically colder than October, with minimum temperatures dropping to -12°C (10°F) and an average of just 4°C (40°F), compared to October’s milder minimum of 2°C (37°F) and an average of 16°C (61°F). While both months experience similar levels of precipitation—approximately 100 mm (4.0 in) in December and 106 mm (4.2 in) in October—the distribution differs slightly, with December seeing about 10 rainy days versus 9 in October. Humidity remains high in both months, but December records a slightly higher rate at 84%, compared to 81% in October. For more specific insights into the weather during October, you can explore Philadelphia weather in October.

In comparing the weather between November and December, it's notable that December experiences a broader temperature range, with minimums plummeting to -12°C (10°F) compared to November's minimum of -8°C (18°F). December averages 4°C (40°F), which is cooler than November's average of 8°C (47°F), while the maximum temperature in December reaches only 19°C (67°F) compared to a warmer 25°C (77°F) in November. Precipitation in December also increases slightly to 100 mm (4.0 in) over 10 days, whereas November sees 83 mm (3.3 in) over 8 days. Humidity levels remain relatively consistent, with December at 84% and November at 85%. For more detailed insights, check out Philadelphia weather in November.

Compare Philadelphia's Climate with Cities Worldwide

Conclusion: What to Expect From December Weather in Philadelphia

As December settles over Philadelphia, the city's weather presents a stark contrast to the milder months that precede it. With temperatures dipping and an unmistakable chill in the air, this winter month often brings frosty mornings and chilly evenings, encouraging residents to bundle up. Coupled with an increase in precipitation—averaging about 100 mm across roughly ten days—December embodies the onset of Philadelphia’s winter season, where the humidity lingers at a brisk 84%, adding to the atmosphere of cold. For a deeper understanding of the climate fluctuations throughout the year, explore Philadelphia Climate.