Philadelphia weather in September: Philadelphia, Pennsylvania: normal highs, lows, rain and records for September
Philadelphia in September has a normal high of 79°F and a normal low of 61°F, a daily mean of 70°F, falling from 84°F on the 1st to 74°F by the 30th. Measurable precipitation falls on 9 days in a normal September, 4.40 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 26°C and low of 16°C, 112 mm of precipitation in September.
- NOAA stationPhiladelphia International Airport
- Station IDUSW00013739
- Location39.87°N 75.23°W
- Elevation10 ft (3 m)
- From the center11 miles
- Population1,573,916
- Jan 41° 26°
- Feb 44° 28°
- Mar 53° 34°
- Apr 65° 44°
- May 74° 54°
- Jun 83° 64°
- Jul 88° 70°
- Aug 86° 68°
- Sep 79° 61°
- Oct 67° 49°
- Nov 56° 39°
- Dec 46° 31°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Philadelphia in September?
The normal high is 79°F and the normal low 61°F, for a daily mean of 69.9°F. September is 6.9°F cooler than August and 11.7°F warmer than October. September is the 4th warmest month of the year in Philadelphia and the wettest. Across the month the normal high falls 10°F, from 84°F on September 1 to 74°F on September 30. From one year to the next September's mean temperature typically moves about 2.2°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 68°F and 72°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 32%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 84°F | 65°F | 28% | 17% |
| September 8 | 82°F | 64°F | 29% | 17% |
| September 15 | 79°F | 61°F | 30% | 18% |
| September 22 | 77°F | 59°F | 31% | 18% |
| September 30 | 74°F | 56°F | 32% | 18% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 84°F | 65°F | 28% | 17% | 13 h 10 min |
| September 2 | 83°F | 65°F | 28% | 17% | 13 h |
| September 3 | 83°F | 65°F | 28% | 17% | 13 h |
| September 4 | 83°F | 65°F | 28% | 17% | 13 h |
| September 5 | 83°F | 64°F | 28% | 17% | 13 h |
| September 6 | 82°F | 64°F | 28% | 17% | 12 h 50 min |
| September 7 | 82°F | 64°F | 28% | 17% | 12 h 50 min |
| September 8 | 82°F | 64°F | 29% | 17% | 12 h 50 min |
| September 9 | 81°F | 63°F | 29% | 17% | 12 h 50 min |
| September 10 | 81°F | 63°F | 29% | 17% | 12 h 40 min |
| September 11 | 81°F | 63°F | 29% | 17% | 12 h 40 min |
| September 12 | 80°F | 62°F | 29% | 17% | 12 h 40 min |
| September 13 | 80°F | 62°F | 29% | 17% | 12 h 40 min |
| September 14 | 80°F | 62°F | 30% | 17% | 12 h 30 min |
| September 15 | 79°F | 61°F | 30% | 18% | 12 h 30 min |
| September 16 | 79°F | 61°F | 30% | 18% | 12 h 30 min |
| September 17 | 79°F | 61°F | 30% | 18% | 12 h 30 min |
| September 18 | 78°F | 60°F | 30% | 18% | 12 h 20 min |
| September 19 | 78°F | 60°F | 30% | 18% | 12 h 20 min |
| September 20 | 78°F | 60°F | 31% | 18% | 12 h 20 min |
| September 21 | 77°F | 59°F | 31% | 18% | 12 h 20 min |
| September 22 | 77°F | 59°F | 31% | 18% | 12 h 10 min |
| September 23 | 76°F | 58°F | 31% | 18% | 12 h 10 min |
| September 24 | 76°F | 58°F | 32% | 18% | 12 h 10 min |
| September 25 | 76°F | 58°F | 32% | 18% | 12 h 10 min |
| September 26 | 75°F | 57°F | 32% | 18% | 12 h |
| September 27 | 75°F | 57°F | 32% | 18% | 12 h |
| September 28 | 74°F | 56°F | 32% | 18% | 12 h |
| September 29 | 74°F | 56°F | 32% | 18% | 11 h 50 min |
| September 30 | 74°F | 56°F | 32% | 18% | 11 h 50 min |
- Normal high
- 79°FSeptember average
- Normal low
- 61°FSeptember average
- Precipitation
- 4.40 inmonth total
- Days with precipitation
- 90.01 inch or more
- Days at 90°F or more
- 2
- Daylight
- 13 h 10 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 27
- Days at 80°F or more
- 14
- Sunshine
- 77%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00013739; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Philadelphia in September?
On a given September day the chance of 0.01 inch or more is 30% on average, highest around September 26 (32%). In all, 4.40 in falls on 9 days of a normal September, 1 of them with an inch or more.
In a normal September in Philadelphia, 2 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00013739.
How humid and windy is Philadelphia in September?
At 3 p.m. the normal temperature is 72°F with 51% relative humidity and a dew point of 53°F; at 6 a.m. it is 59°F with 82% humidity. The wind averages 8.4 mph, most often from the west in the afternoon.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 59°F | 53°F | 82% | 7.1 mph | 41% |
| 9 a.m. | 64°F | 54°F | 69% | 9.2 mph | 40% |
| noon | 70°F | 53°F | 55% | 10.1 mph | 37% |
| 3 p.m. | 72°F | 53°F | 51% | 10.5 mph | 33% |
| 6 p.m. | 68°F | 53°F | 59% | 8.9 mph | 37% |
| 9 p.m. | 64°F | 54°F | 72% | 7.7 mph | 51% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00013739. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for September in Philadelphia?
The warmest September temperature on Philadelphia's official record (since 1873) is 102°F, on September 7, 1881; the coldest is 35°F, on September 25, 1963. The wettest September brought 13.07 in (1999).
The September mean against the 1991-2020 normal of 69.9°F: 2021 71.6°F (+1.7), 2022 72.1°F (+2.2), 2023 71.4°F (+1.5), 2024 70.6°F (+0.7), 2025 73.0°F (+3.1), 2026 72.4°F (+2.5). 6 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 71.6°F | +1.7°F | 4.61 in |
| 2022 | 72.1°F | +2.2°F | 2.06 in |
| 2023 | 71.4°F | +1.5°F | 5.99 in |
| 2024 | 70.6°F | +0.7°F | 0.77 in |
| 2025 | 73.0°F | +3.1°F | 1.79 in |
| 2026 | 72.4°F | +2.5°F | 6.61 in |
Source: records: ACIS, NWS threaded record PHLthr; recent months: ACIS, station USW00013739. Records and recent months use complete months only.
How does September in Philadelphia compare across Pennsylvania?
Across the 108 places PlainClimate covers in Pennsylvania, September normal highs run from 68°F in Laporte to 80°F in Marcus Hook; Philadelphia's is 79°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.
Other months and places
- Philadelphia in August86°F by day, 68°F at night
- Philadelphia in October67°F by day, 49°F at night
- Philadelphia through the yearEvery month, frost dates, records and recent years
- Pennsylvania in SeptemberThe statewide normal and the warmest and coolest places
- Marcus Hook: Pennsylvania's warmest Septembernormal high 80°F