Philadelphia Weather in September
With daytime temperatures of 26°C (79°F) and nighttime lows of 17°C (63°F), September in Philadelphia brings high temperatures during the day. Do keep in mind that quite a bit of rainfall is typical. Around 108 mm (4.3 in) falls on average.
Rainfall in Philadelphia in September
Looking at the last 30 years, the data shows about 8 days with rain, averaging 108 mm (4.3 in) for the month. The rain this month tends to fall in heavier spells rather than light drizzle. When it rains, showers can be significant.
Temperature in Philadelphia in September
In September, expect high temperatures in Philadelphia, with highs of 26°C (79°F) and lows of 17°C (63°F) at night. Conditions stay fairly consistent through the month, making it easier to plan what to wear. At 17°C (63°F) overnight, it can feel quite a bit cooler after dark. Worth packing something warmer for evenings, but the cooler temperatures are ideal for sleeping.
Sunshine in Philadelphia in September
The days are predominantly sunny, with an estimated total of around 218 hours of sunshine. These sun-filled days are perfect for playing sports, visiting parks, or going for a bike ride.
Average water temperature in September
The water is 22°C (72°F) this month — warm enough that getting in requires no effort at all. Good conditions for swimming, snorkeling, or just floating around.If your ideal day consists of dry skies and pleasant temperatures, May typically offers the best circumstances for Philadelphia.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our Philadelphia's climate page.
Philadelphia Temperature in September
Min Temperature
17°C (63°F)
Max Temperature
26°C (79°F)
Water Temperature
22°C (72°F)
Chance of Rain
28%
Precipitation
108 mm (4.3 in)
Rainy days
8 days
Humidity
72%
Sunshine
218 hours
Percentage Sunshine
59%
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Philadelphia typically drop from around 28°C (82°F) at the start of September to approximately 23°C (73°F) by the end. Nights are pleasant, with lows typically ranging from 13°C (55°F) to 19°C (66°F).
Average temperatures in September
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in September
Historical weather for Philadelphia in September
Browse day-by-day weather records for Philadelphia spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Philadelphia historical weather extremes in September
The extremes listed below come from historical weather data collected in Philadelphia from 1976 through 2025.
- Philadelphia recorded its highest September temperature of 36°C (97°F) on September 10, 1983.
- The coldest night in September in Philadelphia was on September 30, 2000, with a minimum of 5°C (41°F).
Best Places in the United States of America in September
Find out more about the weather in the United States of America and which places have the best travel conditions in this month. See all of the United States of America in September →
perfect weather
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What to Wear in Philadelphia in September
Warm temperatures in September make for comfortable sightseeing weather. Pack breathable fabrics like cotton shirts, knee-length shorts or skirts, and comfortable walking shoes. A thin long sleeve for indoor spaces is handy. Prepare for significant rainfall with proper waterproof clothing and shoes. With water temperatures around 22°C (72°F), swimming conditions are excellent. Pack your swimsuit, goggles, and maybe some water shoes. Don't forget sun protection, sunglasses, sunscreen, and a hat. These are all good ideas with this much sunshine.What To Do in Philadelphia in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our Philadelphia's climate page.
Temperature Rainfall Sunshine Humidity Water Temp
See the full Philadelphia climate overview or explore weather in the United States of America.
