Pennsylvania weather in September
September is one of the best months to visit Pennsylvania: highs of 26°C (79°F) and about 102 mm (4.0 in) of rain on average. Nights average 15°C (58°F) and cloud cover 50% (NASA POWER, 2001–2025 averages). It is the 6th wettest month of the year and the 4th warmest. Compared with August, it is cooler and drier; October brings highs of 19°C (66°F) and 110 mm (4.3 in) of rain.
Figures are long-term averages for Philadelphia, the largest city in Pennsylvania. See below for other places.
Is September a good time to visit Pennsylvania?
best month Weather score 73/100.
Yes. September is one of the best months for weather in Pennsylvania.
Does it rain a lot in Pennsylvania in September?
Some rain is normal: about 102 mm (4.0 in) falls in an average September. It is the 6th wettest month of the year.
How warm is Pennsylvania in September?
Days average 26°C (79°F) and nights 15°C (58°F).
Pennsylvania weather by month
| Month | High | Low | Rain | Cloud | Weather |
|---|---|---|---|---|---|
| January | 3°C (38°F) | -5°C (22°F) | 78 mm | 62% | least pleasant |
| February | 5°C (41°F) | -5°C (24°F) | 78 mm | 60% | least pleasant |
| March | 10°C (50°F) | -1°C (30°F) | 100 mm | 60% | least pleasant |
| April | 17°C (62°F) | 5°C (41°F) | 97 mm | 58% | best |
| May | 22°C (72°F) | 11°C (51°F) | 96 mm | 61% | best |
| June | 27°C (80°F) | 16°C (61°F) | 121 mm | 56% | best |
| July | 30°C (86°F) | 19°C (67°F) | 124 mm | 53% | best |
| August | 29°C (85°F) | 19°C (66°F) | 121 mm | 52% | best |
| September | 26°C (79°F) | 15°C (58°F) | 102 mm | 50% | best |
| October | 19°C (66°F) | 8°C (47°F) | 110 mm | 53% | best |
| November | 12°C (54°F) | 2°C (35°F) | 90 mm | 54% | fair |
| December | 6°C (43°F) | -2°C (28°F) | 111 mm | 63% | least pleasant |
Sources: 2001–2025 monthly averages from NASA POWER (MERRA-2 reanalysis). Page updated . How we rate months
Weather across Pennsylvania in September
Weather can differ a lot within Pennsylvania: coasts, hills and mountains each have their own climate.
| Place | High | Low | Rain | Weather |
|---|---|---|---|---|
| Philadelphia | 26°C (79°F) | 15°C (58°F) | 102 mm | best |
| Pittsburgh | 25°C (78°F) | 12°C (54°F) | 85 mm | best |
| Allentown | 25°C (77°F) | 13°C (56°F) | 119 mm | best |
| Erie | 22°C (72°F) | 14°C (57°F) | 93 mm | best |
| Reading | 25°C (77°F) | 13°C (56°F) | 119 mm | best |
| Scranton | 23°C (73°F) | 11°C (51°F) | 118 mm | best |
| Bethlehem | 25°C (77°F) | 13°C (56°F) | 119 mm | best |
| Bensalem | 26°C (79°F) | 15°C (58°F) | 102 mm | best |
| Lancaster | 26°C (78°F) | 14°C (57°F) | 117 mm | best |
| Center City | 26°C (79°F) | 15°C (58°F) | 102 mm | best |
| Abington | 26°C (79°F) | 15°C (58°F) | 102 mm | best |
| Levittown | 26°C (79°F) | 15°C (58°F) | 102 mm | best |