Last spring frost
May 15
Frost Dates for Ellison Bay, WI
First fall frost
Oct 14
Growing season
152 days
Hardiness zone
6a
In an average year around Ellison Bay, WI, the last spring frost (32°F) is about May 15 and the first fall frost is about Oct 14, giving roughly a 152-day growing season. To be safe most years, wait until Apr 30 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 10 | May 28 | May 13 |
| Freeze (32°F) | May 31 | May 15 | Apr 30 |
| Hard (28°F) | May 18 | May 3 | Apr 20 |
| Severe (24°F) | May 5 | Apr 20 | Apr 6 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 10 | Jun 5 | Jun 2 | May 31 | May 28 | May 25 | May 22 | May 18 | May 13 |
| 32°F | May 31 | May 26 | May 21 | May 18 | May 15 | May 12 | May 9 | May 5 | Apr 30 |
| 28°F | May 18 | May 13 | May 9 | May 6 | May 3 | Apr 30 | Apr 28 | Apr 24 | Apr 20 |
| 24°F | May 5 | May 1 | Apr 27 | Apr 24 | Apr 20 | Apr 18 | Apr 15 | Apr 11 | Apr 6 |
| 20°F | Apr 21 | Apr 17 | Apr 13 | Apr 10 | Apr 8 | Apr 5 | Apr 2 | Mar 31 | Mar 25 |
| 16°F | Apr 11 | Apr 6 | Apr 3 | Apr 1 | Mar 30 | Mar 27 | Mar 23 | Mar 20 | Mar 14 |
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 19 | Oct 2 | Oct 16 |
| Freeze (32°F) | Sep 28 | Oct 14 | Oct 31 |
| Hard (28°F) | Oct 10 | Oct 28 | Nov 10 |
| Severe (24°F) | Oct 24 | Nov 7 | Nov 22 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 19 | Sep 24 | Sep 27 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 12 | Oct 16 |
| 32°F | Sep 28 | Oct 2 | Oct 7 | Oct 11 | Oct 14 | Oct 18 | Oct 21 | Oct 25 | Oct 31 |
| 28°F | Oct 10 | Oct 17 | Oct 21 | Oct 25 | Oct 28 | Oct 31 | Nov 3 | Nov 6 | Nov 10 |
| 24°F | Oct 24 | Oct 29 | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 14 | Nov 18 | Nov 22 |
| 20°F | Nov 2 | Nov 8 | Nov 12 | Nov 15 | Nov 18 | Nov 20 | Nov 24 | Nov 28 | Dec 3 |
| 16°F | Nov 13 | Nov 18 | Nov 21 | Nov 24 | Nov 27 | Nov 30 | Dec 3 | Dec 7 | Dec 14 |
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: Washington Is, Wi, about 1.1 miles away@if(!empty($station['elevation_ft'])), at 686 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 Ellison Bay, WI?
On average, the last spring frost (32°F) around Ellison Bay, WI is about May 15. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 30.
When is the first frost in the fall?
The first fall frost around Ellison Bay, WI typically arrives about Oct 14. 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 15 on average, or Apr 30 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 152 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 54246 Planting calendar → Wisconsin frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026