Grundy Ctr, IA: frost dates by year

Last spring and first fall frost at NOAA station USC00133487, 1951 to 2025, measured from daily minimum temperatures.

Elevation 985 ft, 42.365, -92.759. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	May 2	Oct 6
Earliest	Apr 5 (1998)	Sep 15 (2007)
Latest	May 29 (1965)	Oct 28 (1963)
Trend	1.5 days earlier per decade	0.6 days later per decade
Years with data	75	73

At 28°F (hard freeze) the median last spring date is Apr 21 and the median first fall date is Oct 15.

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 23	Apr 16	Oct 24
2024	Apr 21	Oct 15	Apr 6	Oct 16
2023	May 3	Oct 11	Apr 27	Oct 30
2022	Apr 27	Oct 8	Apr 27	Oct 8
2021	May 12	Oct 23	Apr 26	Nov 2
2020	May 12	Oct 4	May 9	Oct 24
2019	May 3	Oct 12	Apr 28	Oct 14
2018	Apr 30	Oct 15	Apr 21	Oct 21
2017	Apr 29	Oct 27	Apr 28	Oct 29
2016	Apr 13	Oct 13	Apr 13	Oct 13
2015	Apr 24	Oct 17	Apr 23	Oct 17
2014	Apr 19	Oct 11	Apr 18	Oct 31
2013	May 13	Oct 20	Apr 24	Oct 22
2012	Apr 21	Sep 23	Apr 13	Oct 6
2011	May 4	Oct 1	May 4	Oct 21
2010	May 10	Oct 3	Mar 30	Oct 29
2009	Apr 16	Oct 10	Apr 15	Oct 10
2008	Apr 30	Oct 16	Apr 29	Oct 28
2007	Apr 16	Sep 15	Apr 13	Oct 25
2006	May 6	Oct 12	Apr 9	Oct 12
2005	May 5	Oct 8	May 3	Oct 26
2004	May 4	Oct 2	May 4	Oct 5
2003	Apr 22	Sep 29	Apr 10	Oct 1
2002	May 3	Sep 24	Apr 26	Oct 16
2001	Apr 19	Oct 6	Apr 19	Oct 6
2000	Apr 26	Oct 6	Apr 13	Oct 7
1999	Apr 19	Oct 4	Mar 27	Oct 4
1998	Apr 5	Oct 8	Mar 25	Oct 22
1997	May 16	Oct 14	Apr 18	Oct 22
1996	Apr 27	Oct 3	Apr 27	Oct 8
1995	Apr 26	Sep 22	Apr 6	Oct 16
1994	May 3	Oct 10	Apr 8	Oct 11
1993	Apr 22	Oct 2	Apr 22	Oct 10
1992	May 7	Sep 29	May 7	Sep 30
1991	Apr 21	Sep 20	Apr 1	Oct 7
1990	May 2	Oct 11	Apr 19	Oct 19
1989	May 8	Sep 23	May 7	Oct 4
1988	Apr 24	Oct 4	Apr 24	Oct 5
1987	Apr 8	Oct 3	Apr 5	Oct 3
1986	Apr 23	Oct 6	Apr 23	Oct 14
1985	Apr 15	Oct 1	Apr 10	Nov 4
1984	Apr 24	Sep 26	Apr 1	Sep 29
1983	Apr 24	Sep 23	Apr 20	Sep 23
1982	Apr 28	Oct 21	Apr 21	Oct 21
1981	May 10	Oct 2	Apr 15	Oct 19
1980	May 9	Sep 26	Apr 16	Oct 12
1979	May 12	Oct 5	Apr 10	Oct 14
1978	May 6	Oct 8	May 2	Oct 26
1977	Apr 26	Oct 6	Apr 7	Oct 16
1976	May 3	Oct 6	Apr 12	Oct 6
1975	Apr 22	Sep 25	Apr 6	Oct 2
1974	May 6	Sep 22	Apr 24	Sep 22
1973	May 15	Oct 20	Apr 28	Nov 5
1972	Apr 26	Sep 30	Apr 9	Oct 15
1971	May 9	Oct 7	May 3	Oct 12
1970	May 2	Oct 10	Apr 11	Oct 16
1969	May 12	Oct 14	Apr 29	Oct 14
1968	May 5	no data	Apr 24	no data
1967	May 22	Sep 29	May 3	Sep 29
1966	May 14	Sep 16	May 14	Oct 1
1965	May 29	Oct 12	Apr 28	Oct 12
1964	Apr 19	Sep 28	Apr 9	Oct 6
1963	May 24	Oct 28	May 23	Oct 29
1962	Apr 20	Sep 20	Apr 17	Oct 24
1961	May 3	no data	May 2	no data
1960	May 8	Oct 16	Apr 18	Oct 19
1959	Apr 22	Oct 9	Apr 21	Oct 12
1958	May 5	Oct 1	Apr 29	Oct 1
1957	May 4	Oct 10	Apr 14	Oct 25
1956	Apr 30	Sep 30	Apr 30	Nov 8
1955	May 8	Oct 18	Mar 29	Oct 24
1954	May 20	Oct 18	May 7	Oct 18
1953	May 13	Oct 26	Apr 27	Oct 27
1952	Apr 16	Oct 3	Apr 15	Oct 5
1951	May 11	Sep 28	May 11	Oct 31

"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.