Last spring frost
May 9
Frost Dates for Bruce, WI
First fall frost
Sep 29
Growing season
140 days
Hardiness zone
4b
In an average year around Bruce, WI, the last spring frost (32°F) is about May 9 and the first fall frost is about Sep 29, giving roughly a 140-day growing season. To be safe most years, wait until Apr 26 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 6 | May 22 | May 7 |
| Freeze (32°F) | May 27 | May 9 | Apr 26 |
| Hard (28°F) | May 15 | Apr 28 | Apr 12 |
| Severe (24°F) | May 1 | Apr 16 | Apr 2 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 6 | Jun 1 | May 29 | May 25 | May 22 | May 19 | May 16 | May 12 | May 7 |
| 32°F | May 27 | May 21 | May 16 | May 12 | May 9 | May 6 | May 3 | Apr 30 | Apr 26 |
| 28°F | May 15 | May 8 | May 3 | Apr 30 | Apr 28 | Apr 25 | Apr 22 | Apr 18 | Apr 12 |
| 24°F | May 1 | Apr 26 | Apr 22 | Apr 19 | Apr 16 | Apr 13 | Apr 9 | Apr 6 | Apr 2 |
| 20°F | Apr 21 | Apr 16 | Apr 11 | Apr 8 | Apr 5 | Apr 3 | Apr 1 | Mar 30 | Mar 24 |
| 16°F | Apr 13 | Apr 8 | Apr 4 | Apr 2 | Mar 31 | Mar 28 | Mar 25 | Mar 22 | Mar 16 |
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 7 | Sep 21 | Oct 3 |
| Freeze (32°F) | Sep 14 | Sep 29 | Oct 14 |
| Hard (28°F) | Sep 24 | Oct 10 | Oct 26 |
| Severe (24°F) | Oct 5 | Oct 25 | Nov 8 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 7 | Sep 12 | Sep 16 | Sep 18 | Sep 21 | Sep 23 | Sep 26 | Sep 30 | Oct 3 |
| 32°F | Sep 14 | Sep 20 | Sep 23 | Sep 26 | Sep 29 | Oct 1 | Oct 4 | Oct 8 | Oct 14 |
| 28°F | Sep 24 | Sep 30 | Oct 3 | Oct 6 | Oct 10 | Oct 13 | Oct 18 | Oct 22 | Oct 26 |
| 24°F | Oct 5 | Oct 13 | Oct 19 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 3 | Nov 8 |
| 20°F | Oct 21 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 7 | Nov 10 | Nov 13 | Nov 18 |
| 16°F | Oct 29 | Nov 2 | Nov 6 | Nov 9 | Nov 12 | Nov 14 | Nov 17 | Nov 21 | Nov 26 |
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: Weyerhaeuser 1N, Wi, about 6.1 miles away@if(!empty($station['elevation_ft'])), at 1,195 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 Bruce, WI?
On average, the last spring frost (32°F) around Bruce, WI is about May 9. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 26.
When is the first frost in the fall?
The first fall frost around Bruce, WI typically arrives about Sep 29. 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 9 on average, or Apr 26 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 140 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 54819 Planting calendar → Wisconsin frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026