Question 1

What is the sunniest time of year in Philadelphia?

Accepted Answer

The sunniest time of year in Philadelphia is mid-to-late summer, with August and July delivering by far the most sunshine in 2025.

August 2025 was the brightest month, recording 348.0 hours of sunshine — roughly 11.2 hours per day. July followed closely with 333.8 hours (about 10.8 hours daily), and September rounded out the top three at 274.3 hours. Across the meteorological summer (June 1 to August 31, 2025), Philadelphia accumulated 932.4 hours of sunshine, averaging 310.8 hours per month. These peak-sun months also brought the year's warmest conditions, with mean temperatures of 26.2°C (79.2°F) in July and 22.7°C (72.9°F) in August.

For contrast, the darkest stretch falls in winter. December 2025 saw just 146.0 hours of sunshine, or about 4.7 hours per day — less than half of an average August day. Over the full year, Philadelphia totaled 2,787.5 hours of sunshine in 2025.

If you're planning outdoor activities, festivals, or sightseeing in Philadelphia, July and August offer the longest, brightest days, making them the ideal window for sun-dependent plans. Just keep in mind that this sunny peak coincides with the city's hottest weather, so early-morning or evening outings can be more comfortable during these high-sunshine months.

Question 2

Which season is the wettest in Philadelphia?

Accepted Answer

Spring is the wettest season in Philadelphia, with the city recording about 385 mm (15.2 inches) of rain during meteorological spring 2025 (March 1 to May 31) — more than any other season.

Summer 2025 (June to August) was a close second at roughly 361 mm (14.2 inches), driven largely by a very wet July. Autumn 2025 (September to November) was noticeably drier at around 215 mm (8.4 inches), while the early-year winter months of January and February 2025 were the driest stretch, totaling just 84 mm (3.3 inches). Across the full calendar year, Philadelphia received approximately 1,142 mm (45.0 inches) of precipitation.

A few monthly extremes stand out in the 2025 data:

- **Wettest month:** July, with 196.5 mm (7.7 inches)
- **Driest month:** January, with 37.3 mm (1.5 inches)
- **Wettest spring month:** May, with 147.2 mm (5.8 inches)

For visitors and residents, this means Philadelphia's rainfall is fairly evenly spread but peaks in the warmer half of the year, when spring showers and summer thunderstorms are most active. If you're planning outdoor activities and want to avoid the heaviest rain, the autumn and mid-winter months tend to be the driest, making them a more reliable bet for clearer conditions in Philadelphia.

Question 3

What were the temperature extremes in Philadelphia in 2025?

Accepted Answer

Philadelphia swung between a scorching high of 38.6°C (101.5°F) and a bitter low of -14.3°C (6.3°F) in 2025, giving the city an exceptionally wide annual temperature range of roughly 52.9°C (95.2°F).

The hottest peak of 2025 arrived in June, when temperatures in Philadelphia spiked to 38.6°C (101.5°F). July followed closely behind with a high of 37.7°C (99.9°F) and was the warmest month overall, averaging 26.2°C (79.2°F). At the other end of the scale, January was the coldest stretch, bottoming out at -14.3°C (6.3°F) and posting a chilly monthly average of -1.7°C (28.9°F). Across the full year, Philadelphia's mean temperature settled at a mild 12.8°C (55.0°F).

This dramatic spread highlights the four-season climate that defines the region. Residents and visitors should plan for genuine heat-wave conditions in midsummer, with hydration and sun protection essential during June and July, while deep winter calls for serious cold-weather layers. The wide gap between the 2025 highs and lows also means the comfortable shoulder seasons of spring and autumn, when daily readings hover in the teens Celsius (50s–60s°F), are often the most pleasant times to explore the city outdoors.

Question 4

What are the average summer temperatures in Philadelphia?

Accepted Answer

Philadelphia averaged a comfortable **24.0°C (75.2°F)** across the summer of 2025, covering the meteorological summer months of June through August (June 1 to August 31).

July was the warmest month in Philadelphia, with a mean temperature of **26.2°C (79.2°F)**. June and August were noticeably milder, averaging 23.1°C (73.6°F) and 22.7°C (72.9°F) respectively. The season's hottest day pushed the thermometer up to **38.6°C (101.5°F)**, while the coolest summer night dipped to 7.8°C (46.0°F), showing how much daily variation Philadelphia experiences even in peak summer.

Summer 2025 was also fairly humid and wet. The average relative humidity sat at 68.7%, and the city collected **361.1 mm (14.2 inches)** of rain over the three months, with July being the rainiest at 196.9 mm.

For visitors and residents, this means Philadelphia summers are warm rather than extreme on average, with pleasant 20s°C (low-to-mid 70s°F) typical for most days. The combination of moderate humidity and occasional hot spells above 35°C (95°F) makes lightweight clothing and hydration sensible, and the frequent July rainfall is worth planning around for outdoor activities. Early mornings and evenings stay mild, making them ideal windows for walking the city or enjoying its parks.

Question 5

What is the weather like in Philadelphia in December?

Accepted Answer

December in Philadelphia is cold and changeable, with temperatures hovering right around freezing. In December 2025, the city recorded a monthly average temperature of just -0.1°C (31.9°F), confirming that early winter brings consistently chilly conditions.

Daytime highs in Philadelphia averaged 4.6°C (40.3°F), while overnight lows fell to an average of -5.0°C (23.1°F). Every single one of the 31 days in December 2025 dropped below freezing at night, and four days stayed below 0°C around the clock. The month also showed wide swings: the warmest afternoon reached 15.8°C (60.4°F) on December 19, while the coldest morning plunged to -11.6°C (11.1°F) on December 9.

December was also fairly wet for Philadelphia. The month saw 92.9 mm (3.66 in) of total precipitation spread across 9 days with measurable rain or melted snow. The wettest day was December 19, which delivered 27.2 mm (1.07 in) alongside breezy conditions. Humidity averaged 70.7% and winds were light to moderate at 13.0 km/h (8.1 mph).

For visitors, this means December in Philadelphia calls for a warm winter coat, layers, and waterproof footwear. Expect frosty mornings and the chance of mixed precipitation, but also the occasional mild day when afternoon highs climb above 10°C (50°F). It is a good time for indoor attractions and holiday markets, with outdoor plans best scheduled around the milder, drier stretches.

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FAQ

What is the sunniest time of year in Philadelphia?

Which season is the wettest in Philadelphia?

What were the temperature extremes in Philadelphia in 2025?

What are the average summer temperatures in Philadelphia?

What is the weather like in Philadelphia in December?