Green Bay, Wisconsin Weather
Day 93 of summer. Read today’s microseason across nine climate regions →
Green Bay weather forecast — hour by hour, 7-day outlook, NOAA radar
Conditions updated 9:25 AM CDT · Open-Meteo
- TodaySep 21Overcast——59°51°—
- TuesdaySep 22Overcast——59°47°0°
- WednesdaySep 23Clear——67°48°+8°
- ThursdaySep 24Overcast——68°52°+1°
- FridaySep 25Overcast——69°56°+1°
- SaturdaySep 26Drizzle—0.20″66°55°-3°
- SundaySep 27Drizzle11%0.11″65°56°-1°
Air quality now AQI 25 · Good
AQI 25 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 7.8 µg/m³, PM10 at 8.3 µg/m³ — typical background levels with no transport signature.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion during the projected peak around 8 PM.
What's driving it
PM × Wind × Precip
PM2.5 at 7.8 µg/m³, PM10 at 8.3 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.94
- Wind
- breezy
- Recent rain
- 0h in last 6h
- Pattern
- background
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
September dries up ditches or breaks down bridges.
- Moonrise
- 4:39 PM
- Moonset
- 12:57 AM
- In sign
- ♑︎ Capricorn
Green Bay at a glance
- Today vs. normal: Today averages 55°F (high 59°F, low 51°F), 7°F below the 62°F normal for Sep 21
- Last frost: May 7 (1991–2020 median, NOAA station 9 km away)
- Microseason: Sep 21–25
- Planting calendar: September — plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, winter squash
16-Day Forecast — Green Bay
- Mon59°51°1%
- Tue59°47°0%
- Wed67°48°0%
- Thu68°52°1%
- Fri69°56°1%
- Sat66°55°5%
- Sun65°56°11%
- Mon71°58°13%
- Tue68°58°29%
- Wed65°49°27%
- Thu61°41°11%
- Fri59°44°16%
- Sat63°53°23%
- Sun58°45°27%
- Mon52°38°24%
- Tue56°34°17%
Forecast data from Open-Meteo (CC BY 4.0).
Live wind & temperature near Green Bay
Interactive wind and temperature map centered on Green Bay — it loads in your browser. Open the full weather map.
Right now in the garden
Fall planting + final harvests
As of September 21, the season's first frost (typically October 9) is approaching. Pick what frost-tender plants still carry before the next cold front. This city's planting calendar for September: plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, and winter squash.
Sun & seasons in Green Bay
Green Bay sits in Brown County, where the year’s longest day runs 15h 33m of daylight and its shortest just 8h 49m — a swing of +6h 44m between the June and December solstices. Clocks spring forward on Sunday, March 8, 2026 and fall back on Sunday, November 1, 2026.
Milwaukee, the state’s largest city, lies about 100 miles to the S. The nearest town Green Bay tracks is Appleton, roughly 26 miles to the SW.
Air quality in Green Bay
Air quality in Green Bay’s county has held roughly steady since 2020; its cleanest year on record was 2024 (median AQI 37). See the full air-quality history for Green Bay.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes | lettuce, spinach, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, spinach, radishes |
| July | tomatoes, peppers, beans, squash, fall brassicas, carrots | lettuce, peas, spinach, beans, summer squash, garlic |
| August | — | peas, tomatoes, peppers, beans, summer squash, garlic |
| September | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash |
| October | — | tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots |
| November | — | fall brassicas, carrots |
A year in weather
Green Bay's warmest month is July (~73°F mean) and its coldest is January (~18°F). Rainfall peaks in June (3.9 inches) and bottoms out in February (1.5 inches).
| Month | Mean temp | Precip |
|---|---|---|
| January | 18° | 1.5″ |
| February | 20° | 1.5″ |
| March | 30° | 2.2″ |
| April | 45° | 2.9″ |
| May | 55° | 3.4″ |
| June | 67° | 3.9″ |
| July | 73° | 3.0″ |
| August | 72° | 3.0″ |
| September | 64° | 3.6″ |
| October | 52° | 2.5″ |
| November | 35° | 2.7″ |
| December | 22° | 1.7″ |
Regional context
Similar climates Allouez, WI, Bellevue, WI, Ashwaubenon, WI
Drawing on modelled 1991-2020 normals (EC_Earth3P_HR model via Open-Meteo), Green Bay's January averages 18°F and July 73°F — 56°F apart — while precipitation totals roughly 31.9 inches.
Summer convection drives Green Bay's precipitation: June logs 3.9 inches, against February's 1.5 inches — warm-season storms carry Green Bay's moisture. Green Bay shares that warm-season-wet pattern with places like Allouez, WI, Bellevue, WI and Ashwaubenon, WI.
Green Bay's growing window opens around May 7, once Green Bay's overnight lows stop freezing — sow kale, peas, spinach, and parsnips. In Green Bay, warm-season transplants — tomatoes, peppers, basil — wait two weeks past Green Bay's frost date. Around October 9, freezing nights resume in Green Bay and tender crops must come in. In about half of years, Green Bay's last freeze comes after May 7.
Similar climates: Allouez, WI, Bellevue, WI, Ashwaubenon, WI, Howard, WI, De Pere, WI.
Frequently asked
- When does it freeze in Green Bay?
- In Green Bay, expect the last spring frost near May 7; Green Bay's first autumn frost comes around October 9.
- What is the rainy season in Green Bay?
- Green Bay sees its heaviest rain in June (around 3.9 inches), part of roughly 32 inches a year.
- What is the warmest month in Green Bay?
- Green Bay peaks in July, when the mean runs near 73°F.
- What is the coldest month in Green Bay?
- January is Green Bay's coldest month, averaging about 18°F.
- When can I start a vegetable garden in Green Bay?
- Around May 7, start frost-hardy crops in Green Bay; tomatoes and basil belong a fortnight later.
- What hardiness zone is Green Bay?
- Since January in Green Bay averages 18°F, Green Bay's USDA zone follows that floor — confirm it by ZIP.
- What is the 10-day forecast for Green Bay?
- Green Bay's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
- Will it rain this week in Green Bay?
- See this week's day-by-day rain chances for Green Bay in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in Green Bay?
- Current conditions for Green Bay and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
- How often is the Green Bay forecast updated?
- The Green Bay forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
- When are sunrise and sunset in Green Bay?
- Today's sunrise and sunset times for Green Bay are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
- How accurate is the weather forecast for Green Bay?
- The next few days in Green Bay's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
Green Bay sits at 44.5°N; its climate zone is warm-summer humid continental (Köppen approximation).
ZIP codes in Green Bay
- 54301
- 54302
- 54303
- 54304
- 54305
- 54306
- 54307
- 54308
- 54311
- 54313