September weather forecast
Wilmington, DE

Bright neon lights light up the Central Business District of Wilmington, Delaware, with a scenic reflection in the Christian River
Bright neon lights light up the Central Business District of Wilmington, Delaware, with a scenic reflection in the Christian River

Weather in September

September, the first month of the autumn, in Wilmington, is still a warm month, with temperature in the range of an average high of 76.3°F (24.6°C) and an average low of 59.9°F (15.5°C).

Temperature

In September, the average high-temperature slightly decreases, from 82.9°F (28.3°C) in August, to a still moderately hot 76.3°F (24.6°C). In Wilmington, the average low-temperature is 59.9°F (15.5°C).

Humidity

In Wilmington, the average relative humidity is 77%.

Rainfall

In Wilmington, during September, the rain falls for 13.3 days and regularly aggregates up to 2.4" (61mm) of precipitation. Throughout the year, in Wilmington, there are 168.9 rainfall days, and 35.55" (903mm) of precipitation is accumulated.

Snowfall

In Wilmington snow does not fall in June through September.

Ocean temperature

In September, the average ocean temperature is 69.8°F (21°C).
Note: For swimming, a surface water temperature of 69.8°F (21°C) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 69.8°F (21°C).

Daylight

In Wilmington, the average length of the day in September is 12.4h.

Sunshine

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

UV index

In Wilmington, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a medium health hazard from unprotected exposure to the Sun's UV rays for the average person.
Note: The daily maximum UV index of 4 interpret into the following advice:
Take precautions - Protection against the skin and eye damage is obliged. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
[Resources]

FAQ

What is the average humidity in September in Wilmington?

The average relative humidity in September in Wilmington is 77%.

How many days does it rain in September in Wilmington?

In Wilmington, during September, the rain falls for 13.3 days and regularly aggregates up to 2.4" (61mm) of precipitation.

When it does not snow in Wilmington?

In Wilmington snow does not fall in June through September.

Does it snow in Wilmington in September?

In Wilmington, Delaware, in September, it doesn't snow. In October, it regularly snows.

How cold is the water in September in Wilmington?

In Wilmington, Delaware, the average seawater temperature in September is 69.8°F (21°C). For most, swimming in 69.8°F (21°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).

How many hours of daylight does Wilmington have in September?

The average length of the day in September is 12.4h.

How many hours of sunshine does Wilmington have in September?

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

What is the UV index intensity in September in Wilmington?

In September, the average daily maximum UV index in Wilmington, Delaware, is 4. A UV Index estimate of 3 to 5 represents a medium health risk from unprotected exposure to the UV radiation.

Average temperature in September
Wilmington, DE

Average temperature in September - Wilmington, DE
  • Average high temperature in September: 76.3°F

The warmest month (with the highest average high temperature) is July (84.9°F).
The month with the lowest average high temperature is January (37°F).

  • Average low temperature in September: 59.9°F

The month with the highest average low temperature is July (68.4°F).
The coldest month (with the lowest average low temperature) is January (25.3°F).

[Resources]

Average pressure in September
Wilmington, DE

Average pressure in September - Wilmington, DE
  • Average pressure in September: 30.05"

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

[Resources]

Average wind speed in September
Wilmington, DE

Average wind speed in September - Wilmington, DE
  • Average wind speed in September: 5.8mph

The windiest months (with the highest average wind speed) are January, February and March (8.6mph).
The calmest month (with the lowest average wind speed) is August (5.4mph).

[Resources]

Average humidity in September
Wilmington, DE

Average humidity in September - Wilmington, DE
  • Average humidity in September: 77%

The month with the highest relative humidity is October (78%).
The month with the lowest relative humidity is April (72%).

[Resources]

Average rainfall in September
Wilmington, DE

Average rainfall in September - Wilmington, DE
  • Average rainfall in September: 2.4"

The wettest month (with the highest rainfall) is August (4.09").
The driest month (with the least rainfall) is January (2.36").

[Resources]

Average rainfall days in September
Wilmington, DE

Average rainfall days in September - Wilmington, DE
  • Average rainfall days in September: 13.3 days

The month with the highest number of rainy days is May (18.7 days).
The month with the least rainy days is November (8.8 days).

[Resources]

Average snowfall in September
Wilmington, DE

Average snowfall in September - Wilmington, DE
  • Average snowfall in September: 0"

The month with the highest snowfall is March (3.58").
Months with the least snowfall are June, July, August and September (0").

[Resources]

Average snowfall days in September
Wilmington, DE

Average snowfall days in September - Wilmington, DE
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (6.8 days).
Months with the least snowfall days are June, July, August and September (0 days).

[Resources]

Average sea temperature in September
Wilmington, DE

Average sea temperature in September - Wilmington, DE
  • Average sea temperature in September: 70°F

The best month for swimming (with the highest average sea temperature) is August (73°F).
The coldest month (with the lowest average sea temperature) is February (34°F).

[Resources]

Average daylight in September /
Average sunshine in September
Wilmington, DE

Average daylight in September / Average sunshine in September - Wilmington, DE
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 15h).
The month with the shortest days is December (Average daylight: 9.4h).

  • Average sunshine in September: 8.8h

The month with the most sunshine is July (Average sunshine: 10.6h).
The month with the least sunshine is February (Average sunshine: 4.9h).

[Resources]

Average sunshine days in September
Wilmington, DE

Average sunshine days in September - Wilmington, DE
  • Average sunshine days in September: 14.2 days

The month with the most sunshine days is November (18.6 days).
Months with the least sunshine days are May and July (9.8 days).

[Resources]

Average UV index in September
Wilmington, DE

Average UV index in September - Wilmington, DE
  • Average UV index in September: 4

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

[Resources]

Average cloud cover in September
Wilmington, DE

Average cloud cover in September - Wilmington, DE
  • Average cloud cover in September: 37

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).

[Resources]

Average visibility in September
Wilmington, DE

Average visibility in September - Wilmington, DE
  • Average visibility in September: 6mi

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

[Resources]

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location
* you will be automatically redirected to the weather forecast for your location