Weather in Philadelphia in September
September in Philadelphia is mild with average temperatures around 20.6°C (69.1°F). Expect significant rainfall with 102mm across approximately 9 days.
Data Note: Temperature values are 2001–2020 satellite/reanalysis grid averages from NASA POWER and may differ from airport station normals by a few degrees.
Temperature
High
26.3°C
79.3°F
Low
14.9°C
58.8°F
Precipitation
102 mm
4.0 inches
~9 rainy days
Conditions
Humidity
74%
Comparison to Adjacent Months
September is 3.5°C cooler than August.
September is 6.8°C warmer than October.