Clinton Wwtp, WI: frost dates by year

Last spring and first fall frost at NOAA station USC00471667, 2002 to 2025, measured from daily minimum temperatures.

Elevation 924 ft, 42.549, -88.876. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	May 6	Oct 10
Earliest	Apr 15 (2007)	Sep 14 (2007)
Latest	May 30 (2021)	Oct 25 (2017)
Trend	4.0 days earlier per decade	5.3 days later per decade
Years with data	22	22

At 28°F (hard freeze) the median last spring date is Apr 22 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	Apr 16	Oct 24	Apr 16	Oct 24
2024	Apr 25	Oct 16	Apr 25	Oct 16
2023	May 3	Oct 10	Apr 26	Oct 30
2022	May 4	Sep 29	Apr 27	Oct 8
2021	May 30	Oct 17	May 11	Oct 23
2020	May 12	Oct 5	May 9	Oct 16
2017	May 7	Oct 25	Apr 1	Oct 29
2016	May 15	Oct 13	Apr 12	Nov 11
2015	May 1	Oct 17	Apr 24	Oct 17
2014	Apr 23	Oct 5	Apr 23	Oct 11
2013	May 13	Oct 20	Apr 20	Oct 22
2012	Apr 27	Sep 23	Apr 12	Oct 8
2011	May 4	Oct 2	Apr 21	Oct 28
2010	May 9	Oct 4	Apr 18	Oct 19
2009	May 17	Oct 10	Apr 12	Oct 10
2008	May 19	Oct 4	Apr 2	Oct 28
2007	Apr 15	Sep 14	Apr 15	Oct 27
2006	Apr 25	Oct 11	Apr 25	Oct 11
2005	May 3	Oct 15	Apr 30	Oct 22
2004	May 22	Oct 1	May 2	Oct 4
2003	May 15	Sep 30	Apr 22	Sep 30
2002	May 20	Oct 12	May 19	Oct 16

"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.