January Weather in Philadelphia, United States

Last updated: June 24, 2025

In Philadelphia, United States, the average temperature in January is a brisk 9°C (48°F), with extremes ranging from a chilling -13°C (8°F) to a balmy 27°C (81°F). Prepare for some wet days, as precipitation averages 110 mm (4.3 in) over 9 days, and humidity hovers around a notable 85%. Stay cozy and enjoy the unique climate!

January Temperature in Philadelphia

In January in Philadelphia, the average temperature is 9°C (48°F), with maximums reaching up to 27°C (81°F) and minimums dropping as low as -13°C (8°F). It's essential to pack accordingly to enjoy all that Philadelphia has to offer during this varied weather.

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

The chart illustrates January 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, January typically has an average temperature of 9°C (48°F), with highs reaching up to 27°C (81°F) and lows dropping to around -13°C (8°F).

Data source: Temperature data for Philadelphia generated using information from the Copernicus Climate Change Service.

January Precipitation in Philadelphia

In Philadelphia in January, the precipitation amount is 110 mm (4.3 in) over the course of 9 days.

January Precipitation Trends in Philadelphia

The chart displays monthly precipitation patterns in Philadelphia, with values for each month alongside January’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how January’s conditions compare to those of other months. In Philadelphia, January typically receives around 110 mm (4.3 inches) of precipitation spread over approximately 9 days.

Data source: Precipitation data for January generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

January Humidity in Philadelphia

In Philadelphia in January humidity is 85%. With an average temperature of 9°C (48°F), this humidity feels like a damp chill enveloping you, making outdoor activities less enjoyable and requiring extra layers to stay warm and comfortable while traveling.

January Average Humidity in Philadelphia

This chart illustrates the average monthly humidity levels in Philadelphia, with January’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In January, average humidity in Philadelphia is approximately 85%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for January generated using information from the Copernicus Climate Change Service.

January UV Index in Philadelphia

In Philadelphia in January, 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 January

The chart shows the monthly maximum UV Index (UVI) for Philadelphia in January, 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 January, the maximum UV index in Philadelphia typically reaches 4, which falls under the moderate exposure category.

Data source: Philadelphia January 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 January 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 January’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 January’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	9°C (48°F)	110 mm (4.3 inches)	85%	moderate
February Weather	11°C (53°F)	173 mm (6.8 inches)	84%	high
March Weather	15°C (60°F)	121 mm (4.8 inches)	82%	very high
April Weather	18°C (64°F)	158 mm (6.2 inches)	82%	very high
May Weather	23°C (73°F)	129 mm (5.1 inches)	82%	extreme
June Weather	26°C (79°F)	168 mm (6.6 inches)	79%	extreme
July Weather	27°C (81°F)	107 mm (4.2 inches)	82%	extreme
August Weather	27°C (80°F)	130 mm (5.1 inches)	77%	extreme
September Weather	25°C (77°F)	93 mm (3.7 inches)	74%	very high
October Weather	20°C (68°F)	106 mm (4.2 inches)	73%	very high
November Weather	12°C (54°F)	68 mm (2.7 inches)	85%	high
December Weather	10°C (51°F)	121 mm (4.8 inches)	88%	moderate