September weather forecast
Green Bay, WI

The sun setting over Green Bay in Wisconsin
The sun setting over Green Bay in Wisconsin

Weather in September

September, the first month of the autumn in Green Bay, is still a pleasant month, with temperature in the range of an average low of 52.3°F (11.3°C) and an average high of 69.6°F (20.9°C).

Temperature

In September, the average high-temperature marginally drops from a moderately hot 77°F (25°C) in August to an agreeable 69.6°F (20.9°C). In September, in Green Bay, the average low-temperature is 52.3°F (11.3°C).

Humidity

In September, the average relative humidity in Green Bay is 79%.

Rainfall

In September, the rain falls for 11.6 days. Throughout September, 1.57" (40mm) of precipitation is accumulated. In Green Bay, during the entire year, the rain falls for 130.8 days and collects up to 24.8" (630mm) of precipitation.

Snowfall

June through September are months without snowfall in Green Bay.

Ocean temperature

In Green Bay, the average water temperature is 63.9°F (17.7°C).
Note: For swimming, a surface water temperature of 63.9°F (17.7°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

The average length of the day in September is 12h and 30min.
On the first day of September, sunrise is at 6:15 am and sunset at 7:28 pm. On the last day of the month, sunrise is at 6:49 am and sunset at 6:34 pm CDT.

Sunshine

In September, the average sunshine in Green Bay is 8.4h.

UV index

In Green Bay, the average daily maximum UV index in September is 3. A UV Index value of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for average individuals.
Note: In September, the average maximum UV index of 3 translate into the following recommendations:
Take precautions - Protection against skin and eye damage is obliged. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.
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FAQ

What is the temperature in September in Green Bay?

In September, in Green Bay, the average high-temperature is 69.6°F (20.9°C), and the average low-temperature is 52.3°F (11.3°C).

What is the average humidity in September in Green Bay?

In Green Bay, Wisconsin, the average relative humidity in September is 79%.

How much does it rain in Green Bay in September?

In Green Bay, during September, the rain falls for 11.6 days and regularly aggregates up to 1.57" (40mm) of precipitation.

When it does not snow in Green Bay?

June through September are months without snowfall.

Does it snow in Green Bay in September?

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

What is the ocean temperature in September in Green Bay?

In Green Bay, Wisconsin, in September, the average water temperature is 63.9°F (17.7°C). Swimming in 63.9°F (17.7°C) is not enjoyable for the majority. Controlling breathing becomes progressively more difficult as surface water temperature decreases below 69.8°F (21°C).

How many hours of daylight does Green Bay have in September?

In September, the average day length in Green Bay is 12h and 30min.

When are sunrise and sunset in September in Green Bay?

In September, on the first day of the month, sunrise is at 6:15 am and sunset at 7:28 pm. On the last day of the month, in Green Bay, sunrise is at 6:49 am and sunset at 6:34 pm CDT.

How many hours of sunshine does Green Bay have in September?

In September, the average sunshine duration is 8.4h.

What is the UV index reading in September in Green Bay?

In Green Bay, Wisconsin, the average daily maximum UV index in September is 3. A UV Index of 3 to 5 symbolizes a moderate health threat from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Green Bay, WI

Average temperature in September - Green Bay, WI
  • Average high temperature in September: 69.6°F

The warmest month (with the highest average high temperature) is July (78.1°F).
The month with the lowest average high temperature is January (22.6°F).

  • Average low temperature in September: 52.3°F

The month with the highest average low temperature is July (60.4°F).
The coldest month (with the lowest average low temperature) is January (12.4°F).

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Average pressure in September
Green Bay, WI

Average pressure in September - Green Bay, WI
  • Average pressure in September: 30.02"Hg

The month with the highest atmospheric pressure is March (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

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Average wind speed in September
Green Bay, WI

Average wind speed in September - Green Bay, WI
  • Average wind speed in September: 8.1mph

The windiest months (with the highest average wind speed) are January and February (10.1mph).
The calmest months (with the lowest average wind speed) are July and August (7.2mph).

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Average humidity in September
Green Bay, WI

Average humidity in September - Green Bay, WI
  • Average humidity in September: 79%

The month with the highest relative humidity is January (88%).
The months with the lowest relative humidity are April and May (76%).

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Average rainfall in September
Green Bay, WI

Average rainfall in September - Green Bay, WI
  • Average rainfall in September: 1.57"

The wettest month (with the highest rainfall) is May (3.31").
The driest month (with the least rainfall) is January (1.18").

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Average rainfall days in September
Green Bay, WI

Average rainfall days in September - Green Bay, WI
  • Average rainfall days in September: 11.6 days

The month with the highest number of rainy days is May (15.9 days).
The month with the least rainy days is February (3.7 days).

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Average snowfall in September
Green Bay, WI

Average snowfall in September - Green Bay, WI
  • Average snowfall in September: 0"

The month with the highest snowfall is February (5.79").
The months with the least snowfall are June, July, August and September (0").

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Average snowfall days in September
Green Bay, WI

Average snowfall days in September - Green Bay, WI
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (15.9 days).
The months with the least snowfall days are June, July, August and September (0 days).

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Average sea temperature in September
Green Bay, WI

Average sea temperature in September - Green Bay, WI
  • Average sea temperature in September: 63.8°F

The best month for swimming (with the highest average sea temperature) is August (67.6°F).
The coldest month (with the lowest average sea temperature) is February (36.1°F).

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Average daylight in September /
Average sunshine in September
Green Bay, WI

Average daylight in September / Average sunshine in September - Green Bay, WI
  • Average daylight in September: 12h and 30min

The month with the longest days is June (Average daylight: 15h and 30min).
The month with the shortest days is December (Average daylight: 8h and 54min).

  • Average sunshine in September: 8h and 24min

The month with the most sunshine is July (Average sunshine: 10h and 6min).
The month with the least sunshine is February (Average sunshine: 3h and 24min).

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Average sunshine days in September
Green Bay, WI

Average sunshine days in September - Green Bay, WI
  • Average sunshine days in September: 17 days

The months with the most sunshine days are September and November (17 days).
The month with the least sunshine days is April (11.6 days).

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Average UV index in September
Green Bay, WI

Average UV index in September - Green Bay, WI
  • Average UV index in September: 3

The months with the highest UV index are June, July and August (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 1).

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Average cloud cover in September
Green Bay, WI

Average cloud cover in September - Green Bay, WI
  • Average cloud cover in September: 35

The month with the most cloud cover is January (Cloud cover 65).
The months with the least cloud cover are July and August (Cloud cover 33).

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Average visibility in September
Green Bay, WI

Average visibility in September - Green Bay, WI
  • Average visibility in September: 6mi

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

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