Last spring frost
May 31
Frost Dates for Herbster, WI
First fall frost
Oct 2
Growing season
123 days
Hardiness zone
4b
In an average year around Herbster, WI, the last spring frost (32°F) is about May 31 and the first fall frost is about Oct 2, giving roughly a 123-day growing season. To be safe most years, wait until May 16 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Jun 20 | Jun 9 | May 29 |
| Freeze (32°F) | Jun 13 | May 31 | May 16 |
| Hard (28°F) | Jun 1 | May 18 | Apr 30 |
| Severe (24°F) | May 19 | May 1 | Apr 16 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 20 | Jun 16 | Jun 14 | Jun 11 | Jun 9 | Jun 6 | Jun 4 | Jun 1 | May 29 |
| 32°F | Jun 13 | Jun 8 | Jun 5 | Jun 2 | May 31 | May 29 | May 26 | May 22 | May 16 |
| 28°F | Jun 1 | May 28 | May 24 | May 21 | May 18 | May 15 | May 10 | May 6 | Apr 30 |
| 24°F | May 19 | May 13 | May 8 | May 4 | May 1 | Apr 29 | Apr 25 | Apr 21 | Apr 16 |
| 20°F | May 5 | Apr 30 | Apr 26 | Apr 22 | Apr 19 | Apr 16 | Apr 12 | Apr 7 | Apr 3 |
| 16°F | Apr 23 | Apr 17 | Apr 13 | Apr 10 | Apr 7 | Apr 4 | Apr 2 | Mar 29 | Mar 24 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Sep 5 | Sep 22 | Oct 5 |
| Freeze (32°F) | Sep 17 | Oct 2 | Oct 14 |
| Hard (28°F) | Sep 27 | Oct 13 | Oct 30 |
| Severe (24°F) | Oct 9 | Oct 28 | Nov 12 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 5 | Sep 11 | Sep 16 | Sep 19 | Sep 22 | Sep 25 | Sep 29 | Oct 1 | Oct 5 |
| 32°F | Sep 17 | Sep 22 | Sep 27 | Sep 30 | Oct 2 | Oct 4 | Oct 7 | Oct 10 | Oct 14 |
| 28°F | Sep 27 | Oct 3 | Oct 6 | Oct 9 | Oct 13 | Oct 16 | Oct 20 | Oct 24 | Oct 30 |
| 24°F | Oct 9 | Oct 15 | Oct 19 | Oct 24 | Oct 28 | Oct 31 | Nov 2 | Nov 6 | Nov 12 |
| 20°F | Oct 22 | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 13 | Nov 16 | Nov 21 |
| 16°F | Nov 1 | Nov 6 | Nov 10 | Nov 13 | Nov 15 | Nov 18 | Nov 21 | Nov 25 | Nov 30 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Port Wing, Wi, about 8.1 miles away@if(!empty($station['elevation_ft'])), at 651 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Herbster, WI?
On average, the last spring frost (32°F) around Herbster, WI is about May 31. In cooler years it can run later, so for a safer bet many gardeners wait until May 16.
When is the first frost in the fall?
The first fall frost around Herbster, WI typically arrives about Oct 2. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around May 31 on average, or May 16 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 123 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 54844 Planting calendar → Wisconsin frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026