Monroe Wwtp, WI: frost dates by year

Last spring and first fall frost at NOAA station USC00475573, 2002 to 2025, measured from daily minimum temperatures.

Elevation 991 ft, 42.599, -89.667. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	May 3	Oct 11
Earliest	Apr 11 (2003)	Sep 23 (2012)
Latest	May 21 (2002)	Oct 29 (2017)
Trend	2.1 days earlier per decade	6.6 days later per decade
Years with data	20	19

At 28°F (hard freeze) the median last spring date is Apr 20 and the median first fall date is Oct 20.

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 17	Oct 24	Apr 16	Oct 24
2024	Apr 22	Oct 16	Apr 22	Oct 16
2023	May 3	Oct 11	Apr 26	Oct 30
2022	Apr 28	Oct 8	Apr 18	Oct 19
2021	May 11	Oct 23	Apr 22	Nov 2
2020	May 10	Oct 16	May 9	Oct 27
2019	Apr 29	Oct 12	Apr 28	Oct 30
2018	Apr 30	Oct 13	Apr 20	Oct 13
2017	May 3	Oct 29	Mar 23	Oct 29
2014	Apr 23	no data	Apr 23	no data
2013	May 13	Oct 14	Apr 21	Oct 20
2012	Apr 27	Sep 23	Apr 12	Oct 8
2011	May 4	Oct 2	May 4	Oct 28
2010	May 9	Oct 4	Apr 9	Oct 22
2009	Apr 22	Oct 10	Apr 9	Oct 10
2008	May 4	Oct 4	Apr 14	Oct 28
2006	no data	Oct 11	no data	Oct 12
2005	May 4	no data	May 4	no data
2004	May 3	Oct 2	Apr 13	Oct 5
2003	Apr 11	Sep 30	Apr 10	Oct 1
2002	May 21	Oct 13	May 3	Oct 19

"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.