Marshalltown, IA: frost dates by year

Last spring and first fall frost at NOAA station USC00135198, 1951 to 2025, measured from daily minimum temperatures.

Elevation 870 ft, 42.065, -92.924. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	Apr 28	Oct 5
Earliest	Apr 4 (1998)	Sep 12 (1955)
Latest	May 23 (1963)	Oct 30 (1973)
Trend	little change (less than half a day per decade)	1.1 days later per decade
Years with data	74	74

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