Frost history / Hales Corners/Whitnall Park/Bo, WI
Hales Corners/Whitnall Park/Bo, WI: frost dates by year
Last spring and first fall frost at NOAA station USC00473391, 2005 to 2025, measured from daily minimum temperatures.
Elevation 774 ft, 42.938, -88.030. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | May 9 | Oct 12 |
| Earliest | Apr 20 (2007) | Sep 19 (2012) |
| Latest | May 30 (2021) | Oct 25 (2017) |
| Trend | 2.4 days earlier per decade | 2.8 days later per decade |
| Years with data | 21 | 21 |
At 28°F (hard freeze) the median last spring date is Apr 24 and the median first fall date is Oct 22.
The trend is a straight-line fit through the years with a freeze. A positive spring trend means the last frost now comes later. Short or patchy records give noisy trends.
Chart
Last spring frost (32°F)
First fall frost (32°F)
Dots are single years. The gray line is the median, the green line the fitted trend.
Year by year
| Year | Last spring 32°F | First fall 32°F | Last spring 28°F | First fall 28°F |
|---|---|---|---|---|
| 2025 | May 9 | Oct 24 | Apr 16 | Nov 6 |
| 2024 | Apr 21 | Oct 17 | Mar 30 | Nov 26 |
| 2023 | Apr 27 | Oct 17 | Apr 24 | Oct 31 |
| 2022 | Apr 28 | Oct 8 | Apr 27 | Oct 27 |
| 2021 | May 30 | Oct 18 | May 30 | Oct 22 |
| 2020 | May 13 | Sep 19 | May 13 | Oct 2 |
| 2019 | May 5 | Oct 12 | Apr 29 | Oct 14 |
| 2018 | May 11 | Oct 12 | Apr 30 | Oct 13 |
| 2017 | May 8 | Oct 25 | Apr 1 | Oct 29 |
| 2016 | May 15 | Oct 14 | Apr 12 | Oct 25 |
| 2015 | May 1 | Oct 17 | Apr 24 | Oct 17 |
| 2014 | Apr 23 | Oct 11 | Apr 16 | Nov 2 |
| 2013 | May 14 | Oct 22 | Apr 21 | Nov 8 |
| 2012 | May 10 | Sep 19 | Apr 28 | Oct 8 |
| 2011 | Apr 22 | Oct 2 | Apr 21 | Oct 24 |
| 2010 | May 10 | Oct 5 | Apr 28 | Oct 22 |
| 2009 | May 19 | Oct 10 | Apr 16 | Oct 10 |
| 2008 | May 19 | Oct 4 | Apr 30 | Oct 4 |
| 2007 | Apr 20 | Oct 14 | Apr 16 | Oct 28 |
| 2006 | May 22 | Oct 12 | Apr 9 | Oct 12 |
| 2005 | May 5 | Oct 21 | May 5 | Oct 21 |
"none" means the station recorded no freeze at that threshold in that half of the year. "no data" means more than 10% of the season's daily readings were missing. Years with no usable data are left out. See the methodology for the rules, and the ZIP lookup for 1991 to 2020 frost probabilities.