September weather forecast
Washington, PA

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Weather in September

September introduces the beginning of the fall season in Washington, with temperatures cooling down to a maximum of 75.7°F (24.3°C). Weather patterns present a decline in both rainfall and daylight hours, indicating the year's transition into its more temperate phase. As the scorching summer heat dwindils, the days gradually shrink, and the vibrant fall colors emerge. The season of change is accentuated by the serene weather, and a sense of calm pervades throughout the city. Thus, September stands as the doorway between the enthusiastic summer and the tranquil autumn, making its mark with a distinctive weather pattern.

Temperature

September's arrival in Washington coincides with a soft drop in the average high-temperature, subtly decreasing from August's 82°F (27.8°C) to a still warm 75.7°F (24.3°C). In September, the average low-temperature records at a fresh 54.9°F (12.7°C) during the nights.

Humidity

The average relative humidity in September is 79%.

Rainfall

In Washington, during September, the rain falls for 11.7 days and regularly aggregates up to 1.02" (26mm) of precipitation. In Washington, during the entire year, the rain falls for 143 days and collects up to 14.8" (376mm) of precipitation.

Snowfall

June through September are months without snowfall in Washington.

Daylight

The average length of the day in September in Washington is 12h and 26min.
On the first day of the month, sunrise is at 6:49 am and sunset at 7:52 pm. On the last day of September, sunrise is at 7:17 am and sunset at 7:04 pm EDT.

Sunshine

In September, the average sunshine in Washington is 8.5h.

UV index

In September, the average daily maximum UV index in Washington is 4. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for the average person.
Note: In September, a daily UV index of 4 turns into the following recommendations:
Guard yourself - Avoiding sunburn is suggested. Limiting exposure to the direct Sun during midday hours can help prevent harmful UV radiation effects. Wearing sunglasses with both UVA and UVB protection effectively reduces sun-induced eye damage.
Updated: Feb 13, 2024 | Published by: Weather U.S. | About Us

Frequently asked questions

What is the temperature in September in Washington?

The average high-temperature and low-temperature in Washington, Pennsylvania, during September are 75.7°F (24.3°C) and 54.9°F (12.7°C) respectively. In August, the average heat index (a.k.a. 'feels like', 'real feel'), which represents the influence of relative humidity on air temperature, is calculated to be 87.8°F (31°C).

What is the average humidity in September in Washington?

In Washington, Pennsylvania, the average relative humidity in September is 79%.

How much does it rain in Washington in September?

In Washington, in September, it is raining for 11.7 days, with typically 1.02" (26mm) of accumulated precipitation.

When it does not snow in Washington?

June through September are months without snowfall in Washington.

Does it snow in Washington in September?

In Washington, Pennsylvania, in September, it doesn't snow. In October, it regularly snows.

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

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

When are sunrise and sunset in September in Washington?

In September, on the first day of the month, sunrise is at 6:49 am and sunset at 7:52 pm. On the last day of the month, sunrise is at 7:17 am and sunset at 7:04 pm EDT.

How long on average sun shines in September in Washington?

The average sunshine duration in September is 8.5h.

What is the UV index reading in September in Washington?

In Washington, Pennsylvania, the average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate vulnerability 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
Washington, PA

Average temperature in September - Washington, PA
  • Average high temperature in September: 75.7°F

The warmest month (with the highest average high temperature) is July (83.3°F).
The month with the lowest average high temperature is January (33.6°F).

  • Average low temperature in September: 54.9°F

The month with the highest average low temperature is July (61.9°F).
The coldest month (with the lowest average low temperature) is January (20.8°F).

Average pressure in September
Washington, PA

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

The month with the highest atmospheric pressure is November (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.95"Hg).

Average wind speed in September
Washington, PA

Average wind speed in September - Washington, PA
  • Average wind speed in September: 5mph

The windiest month (with the highest average wind speed) is January (7.8mph).
The calmest month (with the lowest average wind speed) is August (4.5mph).

Average humidity in September
Washington, PA

Average humidity in September - Washington, PA
  • Average humidity in September: 79%

The month with the highest relative humidity is February (85%).
The months with the lowest relative humidity are April, July and August (77%).

Average rainfall in September
Washington, PA

Average rainfall in September - Washington, PA
  • Average rainfall in September: 1.02"

The wettest month (with the highest rainfall) is July (1.65").
The driest months (with the least rainfall) are January and November (0.94").

Average rainfall days in September
Washington, PA

Average rainfall days in September - Washington, PA
  • Average rainfall days in September: 11.7 days

The month with the highest number of rainy days is May (17.2 days).
The month with the least rainy days is February (7.3 days).

Average snowfall in September
Washington, PA

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

The month with the highest snowfall is February (1.26").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in September
Washington, PA

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

The month with the highest number of snowfall days is January (9.8 days).
The months with the least snowfall days are June, July, August and September (0 days).

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

Average daylight in September / Average sunshine in September - Washington, 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 3min

The month with the most sunshine is August (Average sunshine: 10h and 12min).
The month with the least sunshine is January (Average sunshine: 3h and 0min).

Average sunshine days in September
Washington, PA

Average sunshine days in September - Washington, PA
  • Average sunshine days in September: 15.9 days

The month with the most sunshine days is November (19.1 days).
The month with the least sunshine days is May (11.8 days).

Average UV index in September
Washington, PA

Average UV index in September - Washington, PA
  • Average UV index in September: 4

The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is December (UV index 1).

Average cloud cover in September
Washington, PA

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

The month with the most cloud cover is January (Cloud cover 68).
The month with the least cloud cover is August (Cloud cover 33).

Average visibility in September
Washington, PA

Average visibility in September - Washington, PA
  • Average visibility in September: 5mi

The months with the highest visibility are April and November (6mi).
The months with the lowest visibility are January, February, March, May, June, July, August, September, October and December (5mi).

Washington, Pennsylvania, USA

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