Frost history / Sauk City Wwtp, WI
Sauk City Wwtp, WI: frost dates by year
Last spring and first fall frost at NOAA station USC00477576, 2008 to 2025, measured from daily minimum temperatures.
Elevation 750 ft, 43.262, -89.735. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | May 13 | Oct 11 |
| Earliest | Apr 23 (2014) | Sep 19 (2012) |
| Latest | May 29 (2021) | Oct 29 (2017) |
| Trend | 0.9 days earlier per decade | 7.9 days later per decade |
| Years with data | 17 | 16 |
At 28°F (hard freeze) the median last spring date is Apr 27 and the median first fall date is Oct 18.
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 20 | Apr 17 | Oct 24 |
| 2024 | Apr 26 | Oct 16 | Apr 23 | Oct 16 |
| 2023 | May 26 | Oct 11 | Apr 26 | Oct 30 |
| 2022 | May 23 | Sep 29 | Apr 27 | Oct 15 |
| 2021 | May 29 | Oct 17 | May 12 | Oct 24 |
| 2020 | May 13 | Oct 2 | May 12 | Oct 5 |
| 2019 | Apr 29 | Oct 25 | Apr 28 | Oct 25 |
| 2018 | Apr 30 | Sep 29 | Apr 30 | Oct 13 |
| 2017 | May 4 | Oct 29 | Apr 12 | Oct 29 |
| 2016 | May 18 | Oct 14 | May 16 | Nov 9 |
| 2015 | May 13 | Oct 14 | Apr 27 | Oct 17 |
| 2014 | Apr 23 | Oct 5 | Apr 18 | Oct 10 |
| 2012 | Apr 27 | Sep 19 | Apr 27 | Sep 25 |
| 2011 | May 17 | Oct 1 | May 4 | Oct 19 |
| 2010 | May 10 | Oct 3 | Apr 28 | Oct 22 |
| 2009 | May 17 | Oct 10 | Apr 17 | Oct 10 |
| 2008 | May 28 | no data | May 4 | no data |
"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.