September weather forecast
Philadelphia, PA

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The George Washington statue in front of the Independence Hall in Philadelphia, Pennsylvania
The George Washington statue in front of the Independence Hall in Philadelphia, Pennsylvania

Weather in September

As Philadelphia, Pennsylvania transitions into fall in September, a discernible change in weather occurs. With temperatures reducing significantly from the summer's sweltering heat, September embodies a welcome respite. Compared to August, September experiences a sharp decrease in rainfall to 0.87" (22mm), offering drier days ahead. The city still enjoys plenty of sunlight despite the shortening daylight hours. The fall season ushers in a cooler, calm, and comfortable ambiance throughout Philadelphia.

Temperature

September brings a minor shift in the average high-temperature, adjusting from 84°F (28.9°C) in August to a still moderately hot 76.6°F (24.8°C). September nights in Philadelphia cool down to an average low-temperature of 61.2°F (16.2°C).

Humidity

The average relative humidity in September in Philadelphia is 75%.

Rainfall

In Philadelphia, in September, it is raining for 10.5 days, with typically 0.87" (22mm) of accumulated precipitation. Throughout the year, there are 127.8 rainfall days, and 13.82" (351mm) of precipitation is accumulated.

Snowfall

June through October are months without snowfall.

Ocean temperature

In Philadelphia, in September, the average water temperature is 71.4°F (21.9°C).
Note: Swimming is not an enjoyable activity for the majority when the water is at 71.4°F (21.9°C). The difficulty of controlling breathing increases as the temperature dips from 69.8°F (21°C) to 59°F (15°C).

Daylight

In September, the average length of the day is 12h and 26min.
On the first day of September in Philadelphia, sunrise is at 6:29 am and sunset at 7:31 pm. On the last day of the month, sunrise is at 6:56 am and sunset at 6:44 pm EDT.

Sunshine

In September, the average sunshine in Philadelphia is 8.8h.

UV index

In September, the average daily maximum UV index is 5. A UV Index of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV radiation for the ordinary person.
Note: The maximum daily UV index of 5 in September converts into the following recommendations:
Make use of precautions - Shielding skin and eyes from injury is a requirement. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. Boost your sun resistance with garments that are densely woven yet spacious. Be careful! The Sun's UV radiation is accentuated by reflecting off sand and water.
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Frequently asked questions

What is the usual temperature for Philadelphia in September?

The average high-temperature and low-temperature during September are 76.6°F (24.8°C) and 61.2°F (16.2°C) respectively. In August, the average heat index (a.k.a. 'feels like', 'felt air temperature'), which factors the actual air temperature with the relative humidity, is computed to be 91.4°F (33°C).

What is the average humidity in September in Philadelphia?

In Philadelphia, the average relative humidity in September is 75%.

How much does it rain in Philadelphia in September?

In Philadelphia, Pennsylvania, in September, it is raining for 10.5 days, with typically 0.87" (22mm) of accumulated precipitation.

When it does not snow in Philadelphia?

June through October are months without snowfall in Philadelphia, Pennsylvania.

What is the ocean temperature in September in Philadelphia?

In Philadelphia, the average seawater temperature in September is 71.4°F (21.9°C). For most, swimming in 71.4°F (21.9°C) is not an enjoyable activity. Furthermore, controlling your breathing becomes progressively more difficult as the water temperature decreases from 69.8°F (21°C) to 59°F (15°C).

What is the average length of the day in September in Philadelphia?

In September, the average day length in Philadelphia, Pennsylvania, is 12h and 26min.

What time are sunrise and sunset in September in Philadelphia?

In September, on the first day of the month, sunrise is at 6:29 am and sunset at 7:31 pm. On the last day of the month, in Philadelphia, Pennsylvania, sunrise is at 6:56 am and sunset at 6:44 pm EDT.

How many hours of sunshine does Philadelphia have in September?

In Philadelphia, Pennsylvania, the average sunshine duration in September is 8.8h.

What is the UV index reading in September in Philadelphia?

The average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a medium hazard to health from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Philadelphia, PA

Average temperature in September - Philadelphia, PA
  • Average high temperature in September: 76.6°F

The warmest month (with the highest average high temperature) is July (86.4°F).
The month with the lowest average high temperature is January (37.4°F).

  • Average low temperature in September: 61.2°F

The month with the highest average low temperature is July (69.3°F).
The coldest month (with the lowest average low temperature) is January (25.5°F).

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Average pressure in September
Philadelphia, PA

Average pressure in September - Philadelphia, PA
  • Average pressure in September: 30.05"Hg

The month with the highest atmospheric pressure is November (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).

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Average wind speed in September
Philadelphia, PA

Average wind speed in September - Philadelphia, PA
  • Average wind speed in September: 6mph

The windiest months (with the highest average wind speed) are March and April (8.5mph).
The calmest month (with the lowest average wind speed) is August (5.6mph).

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Average humidity in September
Philadelphia, PA

Average humidity in September - Philadelphia, PA
  • Average humidity in September: 75%

The month with the highest relative humidity is October (77%).
The months with the lowest relative humidity are April and August (71%).

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Average rainfall in September
Philadelphia, PA

Average rainfall in September - Philadelphia, PA
  • Average rainfall in September: 0.87"

The wettest month (with the highest rainfall) is August (1.65").
The driest months (with the least rainfall) are January and February (0.83").

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Average rainfall days in September
Philadelphia, PA

Average rainfall days in September - Philadelphia, PA
  • Average rainfall days in September: 10.5 days

The month with the highest number of rainy days is July (14.8 days).
The month with the least rainy days is February (7.2 days).

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Average snowfall in September
Philadelphia, PA

Average snowfall in September - Philadelphia, PA
  • Average snowfall in September: 0"

The month with the highest snowfall is February (0.98").
The months with the least snowfall are June, July, August, September and October (0").

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Average snowfall days in September
Philadelphia, PA

Average snowfall days in September - Philadelphia, PA
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (3.8 days).
The months with the least snowfall days are June, July, August, September and October (0 days).

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Average sea temperature in September
Philadelphia, PA

Average sea temperature in September - Philadelphia, PA
  • Average sea temperature in September: 71.4°F

The best month for swimming (with the highest average sea temperature) is August (75.9°F).
The coldest month (with the lowest average sea temperature) is February (39.9°F).

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Average daylight in September /
Average sunshine in September
Philadelphia, PA

Average daylight in September / Average sunshine in September - Philadelphia, PA
  • Average daylight in September: 12h and 2min

The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).

  • Average sunshine in September: 8h and 5min

The month with the most sunshine is July (Average sunshine: 10h and 36min).
The month with the least sunshine is February (Average sunshine: 4h and 48min).

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Average sunshine days in September
Philadelphia, PA

Average sunshine days in September - Philadelphia, PA
  • Average sunshine days in September: 17.4 days

The month with the most sunshine days is December (20.9 days).
The month with the least sunshine days is May (13.3 days).

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Average UV index in September
Philadelphia, PA

Average UV index in September - Philadelphia, PA
  • Average UV index in September: 5

The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).

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Average cloud cover in September
Philadelphia, PA

Average cloud cover in September - Philadelphia, PA
  • Average cloud cover in September: 38

The months with the most cloud cover are February and March (Cloud cover 47).
The month with the least cloud cover is July (Cloud cover 31).

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Average visibility in September
Philadelphia, PA

Average visibility in September - Philadelphia, PA
  • Average visibility in September: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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Philadelphia, Pennsylvania, USA

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