September weather forecast
Winterthur, DE

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Weather in September

The first month of the autumn, September, is also a moderately hot month in Winterthur, Delaware, with an average temperature fluctuating between 76.3°F (24.6°C) and 59.9°F (15.5°C).

Temperature

The average high-temperature shows a slight dip in September, from August's 82.9°F (28.3°C) to a still moderately hot 76.3°F (24.6°C). Winterthur, during September, witnesses an average low-temperature of 59.9°F (15.5°C).

Humidity

In Winterthur, the average relative humidity in September is 77%.

Rainfall

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

Snowfall

June through September are months without snowfall.

Daylight

The average length of the day in September is 12h and 26min.
On the first day of September, sunrise is at 6:31 am and sunset at 7:33 pm. On the last day of the month, sunrise is at 6:58 am and sunset at 6:45 pm EDT.

Sunshine

In Winterthur, Delaware, the average sunshine in September is 8.8h.

UV index

In September, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to UV radiation for the average person.
Note: During September, 4 as the daily maximum UV index converts into the following advice:
Guard yourself - Precautionary measures against sun damage are advocated. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. For holistic sun protection encompassing the eyes, ears, face, and neck, a wide-brim hat is key.
Updated: Jul 13, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are September temperatures?

In Winterthur, 76.3°F (24.6°C) is the average high-temperature and 59.9°F (15.5°C) is the average low-temperature during September. In August, the average heat index (a.k.a. 'apparent temperature', 'felt air temperature'), which combines air temperature and relative humidity, is computed to be 89.6°F (32°C).

What is the average humidity in September?

In Winterthur, the average relative humidity in September is 77%.

How much does it rain in September?

In September, the rain falls for 13.3 days. Throughout September, 2.4" (61mm) of precipitation is accumulated.

When it does not snow?

June through September are months without snowfall in Winterthur.

Does it snow in September?

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

How many hours of daylight does Winterthur have in September?

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

When is the sunrise / sunset in September?

In September, on the first day of the month, sunrise is at 6:31 am and sunset at 7:33 pm. On the last day of the month, sunrise is at 6:58 am and sunset at 6:45 pm EDT.

How many hours of sunshine does Winterthur have in September?

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

What is the UV index reading in September in Winterthur?

In Winterthur, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium hazard to health from exposure to the Sun's UV radiation.
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
Winterthur, DE

Average temperature in September - Winterthur, 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).

Average pressure in September
Winterthur, DE

Average pressure in September - Winterthur, DE
  • 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).

Average wind speed in September
Winterthur, DE

Average wind speed in September - Winterthur, 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).

Average humidity in September
Winterthur, DE

Average humidity in September - Winterthur, 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%).

Average rainfall in September
Winterthur, DE

Average rainfall in September - Winterthur, 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").

Average rainfall days in September
Winterthur, DE

Average rainfall days in September - Winterthur, 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).

Average snowfall in September
Winterthur, DE

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

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

Average snowfall days in September
Winterthur, DE

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

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

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

Average daylight in September / Average sunshine in September - Winterthur, DE
  • Average daylight in September: 12h and 2min

The month with the longest days is June (Average daylight: 14h and 54min).
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 54min).

Average sunshine days in September
Winterthur, DE

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

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

Average UV index in September
Winterthur, DE

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

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).

Average cloud cover in September
Winterthur, DE

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

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).

Average visibility in September
Winterthur, DE

Average visibility in September - Winterthur, DE
  • 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).

Winterthur, Delaware, USA

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