USDA Hardiness Zone 5b
Frost Dates for 54304 — Green Bay, Wisconsin
NOAA 1991–2020 normals from Green Bay, WI (682 ft), 2 miles west.
Updated
In Green Bay, the last spring frost (32°F) is around April 30 in half of years and has passed by May 16 in nine years out of ten. The first fall frost comes around October 9, as early as September 24 one year in ten, leaving a typical freeze-free season of 161 days (NOAA, Green Bay, WI).
- Last spring frost
- April 30
- First fall frost
- October 9
- Growing season
- 161 days
- Hardiness zone
- 5b
50% probability
50% probability
freeze-free, 50%
-15 to -10°F (-26.1 to -23.3°C) coldest night
- First snow
- November 12
- Last snow
- April 13
- Winters with snow
- 100%
- Snow per year
- 55.6"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Green Bay
Half of springs at Green Bay, WI see their last 32°F night by April 30; only one in ten is past it by April 16, and one in ten still has one after May 16. Planting tender crops after May 7 leaves a 30% risk of a frost on them, after May 11 20%, and after May 16 10%. The 16 days between the even-odds date and the one-in-ten date is wider than at 70% of the 182 Wisconsin stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 9 in half of years, as early as September 24 one year in ten, and holds off past October 26 one year in ten. A hard freeze of 28°F follows 15 days later, around October 24; in spring the one-in-ten date for 28°F is May 4, 12 days before the 32°F one. The freeze-free season lasts 161 days in a typical year, longer than at 62% of the 182 Wisconsin stations; it reaches 181 days one year in ten and falls short of 141 one year in ten. On average 152 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 13 days longer, to about May 13, and return around September 29. Severe cold of 16°F or below comes every winter, usually between November 25 and March 20.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 29 | May 2 | May 6 | May 9 | May 13 | May 16 | May 19 | May 23 | May 27 |
| 32°F | Apr 16 | Apr 22 | Apr 25 | Apr 29 | Apr 30 | May 4 | May 7 | May 11 | May 16 |
| 28°F | Apr 3 | Apr 7 | Apr 11 | Apr 15 | Apr 17 | Apr 21 | Apr 24 | Apr 29 | May 4 |
| 24°F | Mar 22 | Mar 28 | Apr 1 | Apr 3 | Apr 5 | Apr 8 | Apr 12 | Apr 16 | Apr 21 |
| 20°F | Mar 13 | Mar 18 | Mar 22 | Mar 26 | Mar 29 | Mar 31 | Apr 3 | Apr 6 | Apr 11 |
| 16°F | Mar 6 | Mar 10 | Mar 14 | Mar 17 | Mar 20 | Mar 24 | Mar 27 | Mar 31 | Apr 4 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 16 | Sep 20 | Sep 24 | Sep 26 | Sep 29 | Oct 1 | Oct 4 | Oct 7 | Oct 12 |
| 32°F | Sep 24 | Sep 29 | Oct 3 | Oct 6 | Oct 9 | Oct 12 | Oct 16 | Oct 21 | Oct 26 |
| 28°F | Oct 6 | Oct 11 | Oct 16 | Oct 21 | Oct 24 | Oct 28 | Nov 1 | Nov 3 | Nov 9 |
| 24°F | Oct 21 | Oct 28 | Nov 1 | Nov 2 | Nov 6 | Nov 9 | Nov 12 | Nov 17 | Nov 22 |
| 20°F | Nov 1 | Nov 6 | Nov 10 | Nov 14 | Nov 17 | Nov 20 | Nov 23 | Nov 26 | Dec 1 |
| 16°F | Nov 10 | Nov 16 | Nov 19 | Nov 23 | Nov 25 | Nov 28 | Dec 1 | Dec 4 | Dec 10 |
Freeze probabilities 1991–2020 at Green Bay, WI, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 54304 →Compare Green Bay with another place →
Weather by month in Green Bay
July is the warmest month at Green Bay, WI, averaging 81°F by day and 60°F at night; January is the coldest at 26°F and 11°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 50% of years.
Warmth for growing adds up to 2,428 growing degree days a year (base 50°F), more than at 51% of the 182 Wisconsin stations. 32% of them (778) have built up by the end of June, and July adds the most, 637. Precipitation totals 31.8 inches a year, most in June (4.1") and least in February (1.2"); May to September bring 56% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 26 | 11 | 1.4 | 100% | 30 | 0 |
| Feb | 29 | 13 | 1.2 | 100% | 27 | 0 |
| Mar | 40 | 24 | 2.0 | 100% | 25 | 9 |
| Apr | 54 | 35 | 3.0 | 99% | 12 | 44 |
| May | 67 | 46 | 3.4 | 50% | 1 | 234 |
| Jun | 77 | 56 | 4.1 | 0% | 0 | 492 |
| Jul | 81 | 60 | 3.6 | 0% | 0 | 637 |
| Aug | 79 | 58 | 3.4 | 0% | 0 | 575 |
| Sep | 72 | 50 | 3.2 | 22% | 1 | 337 |
| Oct | 58 | 40 | 2.7 | 94% | 8 | 91 |
| Nov | 44 | 29 | 2.0 | 100% | 21 | 9 |
| Dec | 31 | 18 | 1.8 | 100% | 28 | 0 |
Monthly normals 1991–2020 at Green Bay, WI (682 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Green Bay WFO, WI, 2 miles west of Green Bay, has a last frost 1 day later (May 1), a first frost 2 days later (October 11), a season 1 day shorter.
When it snows in Green Bay, Wisconsin
The first measurable snow (0.1 inch or more) in Green Bay usually arrives around November 12, and the last of the season around April 13. Those are the middle dates across the winters of 1991–2020 at Green Bay, WI, 2.4 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 17 days after the last snow.
Planting calendar for 54304
| When | What to do |
|---|---|
| February 19 – March 5 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 5 – March 19 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 2 – April 16 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 30 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 17 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 25 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 9 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 54304 is 2 miles from Green Bay, WI, which stands at 682 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 54115 (De Pere). The 2023 USDA Plant Hardiness Zone Map lists ZIP 54304 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.
Frost dates across Wisconsin →
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.