Weather in Philadelphia in September 2025
- September is usually the wettest month of the year in Philadelphia;
Average weather
Average temperature in Philadelphia in September
The expected average maximum temperature in September is +26°C with a maximum of +36°C and a minimum of +12°C.
The average maximum temperature goes down 21% by the end of the month, compared with the beginning of the month, from +26°C to +21°C.
Is Philadelphia warm or cold in September?
Philadelphia is typically warm in September.
Maximum temperatures go down compared to the previous month from +29°C to +26°C. The minimum temperature also goes down from +21°C to +17°C.
It’s generally warm, but pack a long-sleeve shirt for evenings.
Take a look at how September is compared to other months in Philadelphia:
Climate in Philadelphia in September
| August | September | October | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +29°C | +26°C | +19°C | ||||
| Min. temperature | ||||||
| +9°C | +4°C | -2°C | ||||
| Max. temperature | ||||||
| +38°C | +36°C | +34°C | ||||
| Rainfall | ||||||
| 96 mm | 101 mm | 91 mm | ||||
| Wind | ||||||
| 2 m/s | 2 m/s | 3 m/s | ||||
| Humidity | ||||||
| 71% | 72% | 71% | ||||
| Air pressure | ||||||
| 1015 HPa | 1017 HPa | 1017 HPa | ||||
| Sunny days | ||||||
| 5 | 7 | 8 | ||||
| Cloudy days | ||||||
| 10 | 11 | 12 | ||||
| Rainy days | ||||||
| 15 | 12 | 12 | ||||
| Snowy days | ||||||
| 0 | 0 | 0 | ||||
September weather is still as good as in August. It’s getting colder in September. From +29°C in the day, the average maximum temperature lowers to +26°C. Prepare for more rain. Average rainfall goes from 96 mm to 101 mm. Humidity rises from 71% to 72%. The average wind speed doesn’t change much during September, staying around 2 m/s. The good news is there are likely to be more sunny days in September, from 5 to 7.
October brings much the same weather, it remains good.
Wind
The average wind speed is 3 m/s getting up to 8 m/s which is a medium breeze. You can feel it, especially getting out of the water.
The average wind speed in Philadelphia is gradually increasing during September, going from 3 m/s to 4 m/s over the course of the month.
Rain
How was the weather last September in Philadelphia?
Climate Change over Years
The climate in Philadelphia in September has not changed much over the last 43 years.
The average temperature was the lowest in 1996 (+17°C) and the highest in 2012 (+20°C). The driest year was 2001 with only 685 mm of rainfall, and the wettest year was 2023 with 1758 mm.
FAQ
Is September a good time to visit Philadelphia?
Can you sunbathe in Philadelphia in September?
Is Philadelphia rainy in September?
Is it sunny in Philadelphia in September?
Other cities in USA
Monthly weather in Philadelphia
Source of the data
For this page, we’ve looked at the typical weather in Philadelphia, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.