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September Weather in Green Bay, United States

Last updated: June 24, 2025

In Green Bay, United States, the average temperature in September is a comfortable 17°C (63°F), with lows dipping to 1°C (33°F) and highs reaching up to 33°C (92°F). During this time, expect about 65 mm (2.5 in) of precipitation spread over 10 days, contributing to an overall average humidity of 78%.

September Temperature in Green Bay

In September in Green Bay, the average temperature is 17°C (63°F). Maximum temperatures can reach 33°C (92°F), while the minimum can drop as low as 1°C (33°F). It's advisable to pack layers to accommodate the varying temperatures during your travels.

September Weather in Green Bay: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Green Bay, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Green Bay, September typically has an average temperature of 17°C (63°F), with highs reaching up to 33°C (92°F) and lows dropping to around 1°C (33°F).
JanFebMarAprMayJunJulAugSepOctNovDec212133435668737063503527
Data source: Temperature data for Green Bay generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Green Bay

In Green Bay in September, the total precipitation amount is 65 mm (2.5 in) over the course of 10 days.

September Precipitation Trends in Green Bay

The chart displays monthly precipitation patterns in Green Bay, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Green Bay, September typically receives around 65 mm (2.5 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec4048599910610610810765944854
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Green Bay

In Green Bay in September, humidity is 78%. With an average temperature of 17°C (63°F), this humidity feels like a warm, enveloping blanket, making traveling slightly uncomfortable as you navigate the sticky air, prompting the need for frequent breaks in cooler, shaded areas.

September Average Humidity in Green Bay

This chart illustrates the average monthly humidity levels in Green Bay, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Green Bay is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec89%90%87%84%77%75%75%73%78%84%89%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Green Bay

In Green Bay in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Green Bay.

Maximum UV Index Levels in Green Bay for September

The chart shows the monthly maximum UV Index (UVI) for Green Bay in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Green Bay typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2457910997532
Data source: Green Bay September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Green Bay Compares to Other Months

Weather in Green Bay varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Green Bay, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Green Bay, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-6°C (21°F)40 mm (1.6 inches)89%low
February Weather-6°C (21°F)48 mm (1.9 inches)90%moderate
March Weather1°C (33°F)59 mm (2.3 inches)87%moderate
April Weather6°C (43°F)99 mm (3.9 inches)84%high
May Weather14°C (57°F)106 mm (4.2 inches)77%very high
June Weather20°C (68°F)106 mm (4.2 inches)75%very high
July Weather23°C (73°F)108 mm (4.2 inches)74%very high
August Weather21°C (70°F)107 mm (4.2 inches)73%very high
September Weather17°C (63°F)65 mm (2.5 inches)78%high
October Weather10°C (50°F)94 mm (3.7 inches)84%moderate
November Weather2°C (35°F)48 mm (1.9 inches)89%moderate
December Weather-3°C (27°F)54 mm (2.1 inches)87%low

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