Green Bay weather in September: Green Bay, Wisconsin: normal highs, lows, rain and records for September
Green Bay in September has a normal high of 72°F and a normal low of 50°F, a daily mean of 61°F, falling from 76°F on the 1st to 66°F by the 30th. Measurable precipitation falls on 10 days in a normal September, 3.20 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 22°C and low of 10°C, 81 mm of precipitation in September.
- NOAA stationGreen Bay A S International Airport
- Station IDUSW00014898
- Location44.50°N 88.11°W
- Elevation682 ft (208 m)
- From the center6 miles
- Population106,311
- Jan 26° 11°
- Feb 29° 13°
- Mar 40° 24°
- Apr 54° 35°
- May 67° 46°
- Jun 77° 56°
- Jul 81° 60°
- Aug 79° 58°
- Sep 72° 50°
- Oct 58° 40°
- Nov 44° 29°
- Dec 31° 18°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Green Bay in September?
The normal high is 72°F and the normal low 50°F, for a daily mean of 61.0°F. September is 7.6°F cooler than August and 12.3°F warmer than October. September is the 4th warmest month of the year in Green Bay and the 5th wettest. Across the month the normal high falls 10°F, from 76°F on September 1 to 66°F on September 30. From one year to the next September's mean temperature typically moves about 2.9°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 58°F and 64°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 34%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 76°F | 55°F | 31% | 20% |
| September 8 | 75°F | 53°F | 32% | 20% |
| September 15 | 72°F | 51°F | 33% | 20% |
| September 22 | 69°F | 48°F | 34% | 20% |
| September 30 | 66°F | 45°F | 34% | 20% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 76°F | 55°F | 31% | 20% | 13 h 20 min |
| September 2 | 76°F | 55°F | 31% | 20% | 13 h 10 min |
| September 3 | 76°F | 55°F | 31% | 20% | 13 h 10 min |
| September 4 | 76°F | 54°F | 31% | 20% | 13 h 10 min |
| September 5 | 75°F | 54°F | 31% | 20% | 13 h 10 min |
| September 6 | 75°F | 54°F | 31% | 20% | 13 h |
| September 7 | 75°F | 53°F | 31% | 20% | 13 h |
| September 8 | 75°F | 53°F | 32% | 20% | 13 h |
| September 9 | 74°F | 53°F | 32% | 20% | 12 h 50 min |
| September 10 | 74°F | 52°F | 32% | 20% | 12 h 50 min |
| September 11 | 74°F | 52°F | 32% | 20% | 12 h 50 min |
| September 12 | 73°F | 52°F | 32% | 20% | 12 h 40 min |
| September 13 | 73°F | 51°F | 32% | 20% | 12 h 40 min |
| September 14 | 73°F | 51°F | 32% | 20% | 12 h 40 min |
| September 15 | 72°F | 51°F | 33% | 20% | 12 h 40 min |
| September 16 | 72°F | 50°F | 33% | 20% | 12 h 30 min |
| September 17 | 72°F | 50°F | 33% | 20% | 12 h 30 min |
| September 18 | 71°F | 49°F | 33% | 20% | 12 h 30 min |
| September 19 | 71°F | 49°F | 33% | 20% | 12 h 20 min |
| September 20 | 70°F | 49°F | 34% | 20% | 12 h 20 min |
| September 21 | 70°F | 48°F | 34% | 20% | 12 h 20 min |
| September 22 | 69°F | 48°F | 34% | 20% | 12 h 10 min |
| September 23 | 69°F | 48°F | 34% | 20% | 12 h 10 min |
| September 24 | 69°F | 47°F | 34% | 20% | 12 h 10 min |
| September 25 | 68°F | 47°F | 34% | 20% | 12 h 10 min |
| September 26 | 68°F | 46°F | 34% | 20% | 12 h |
| September 27 | 67°F | 46°F | 34% | 20% | 12 h |
| September 28 | 67°F | 46°F | 34% | 20% | 12 h |
| September 29 | 66°F | 45°F | 34% | 20% | 11 h 50 min |
| September 30 | 66°F | 45°F | 34% | 20% | 11 h 50 min |
- Normal high
- 72°FSeptember average
- Normal low
- 50°FSeptember average
- Precipitation
- 3.20 inmonth total
- Days with precipitation
- 100.01 inch or more
- Nights at 32°F or colder
- 1
- Daylight
- 13 h 20 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 19
- Days at 80°F or more
- 6
- Sunshine
- 76%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00014898; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Green Bay in September?
On a given September day the chance of 0.01 inch or more is 33% on average, highest around September 29 (34%). In all, 3.20 in falls on 10 days of a normal September, 1 of them with an inch or more.
In a normal September in Green Bay, 1 nights fall to freezing.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00014898.
How humid and windy is Green Bay in September?
At 3 p.m. the normal temperature is 63°F with 54% relative humidity and a dew point of 47°F; at 6 a.m. it is 48°F with 88% humidity. The wind averages 8.1 mph, most often from the west-southwest in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 48°F | 44°F | 88% | 6.4 mph | 56% |
| 9 a.m. | 57°F | 48°F | 72% | 9.8 mph | 53% |
| noon | 62°F | 47°F | 57% | 11.1 mph | 51% |
| 3 p.m. | 63°F | 47°F | 54% | 10.8 mph | 53% |
| 6 p.m. | 57°F | 47°F | 70% | 7.2 mph | 56% |
| 9 p.m. | 52°F | 47°F | 80% | 6.8 mph | 57% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00014898. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for September in Green Bay?
The warmest September temperature on Green Bay's official record (since 1886) is 97°F, on September 10, 1931; the coldest is 24°F, on September 29, 1949. The wettest September brought 9.37 in (2019).
The September mean against the 1991-2020 normal of 61.0°F: 2021 62.7°F (+1.7), 2022 62.8°F (+1.8), 2023 64.6°F (+3.6), 2024 65.8°F (+4.8), 2025 62.4°F (+1.4), 2026 63.1°F (+2.1). 6 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 62.7°F | +1.7°F | 1.17 in |
| 2022 | 62.8°F | +1.8°F | 3.30 in |
| 2023 | 64.6°F | +3.6°F | 0.51 in |
| 2024 | 65.8°F | +4.8°F | 0.84 in |
| 2025 | 62.4°F | +1.4°F | 1.77 in |
| 2026 | 63.1°F | +2.1°F | 5.73 in |
Source: records: ACIS, NWS threaded record GRBthr; recent months: ACIS, station USW00014898. Records and recent months use complete months only.
How does September in Green Bay compare across Wisconsin?
Across the 165 places PlainClimate covers in Wisconsin, September normal highs run from 64°F in Laona to 77°F in West Allis; Green Bay's is 72°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.
Other months and places
- Green Bay in August79°F by day, 58°F at night
- Green Bay in October58°F by day, 40°F at night
- Green Bay through the yearEvery month, frost dates, records and recent years
- Wisconsin in SeptemberThe statewide normal and the warmest and coolest places
- West Allis: Wisconsin's warmest Septembernormal high 77°F