Charles City, IA: frost dates by year

Last spring and first fall frost at NOAA station USC00131402, 1951 to 2025, measured from daily minimum temperatures.

Elevation 993 ft, 43.060, -92.672. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	May 2	Oct 4
Earliest	Apr 6 (1987)	Sep 12 (1955)
Latest	May 23 (1963)	Oct 30 (1973)
Trend	little change (less than half a day per decade)	little change (less than half a day per decade)
Years with data	75	75

At 28°F (hard freeze) the median last spring date is Apr 18 and the median first fall date is Oct 14.

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 23	Apr 8	Oct 24
2024	Apr 24	Oct 15	Apr 5	Oct 16
2023	May 3	Oct 10	Apr 26	Oct 28
2022	May 4	Sep 28	Apr 26	Oct 8
2021	May 11	Oct 22	Apr 25	Oct 23
2020	May 12	Oct 2	May 9	Oct 19
2019	Apr 28	Oct 12	Apr 28	Oct 14
2018	Apr 29	Oct 12	Apr 20	Oct 21
2017	Apr 28	Oct 27	Apr 28	Oct 28
2016	May 15	Oct 13	May 15	Oct 13
2015	Apr 28	Oct 17	Apr 23	Oct 17
2014	May 17	Oct 10	Apr 18	Oct 31
2013	May 12	Oct 19	Apr 24	Oct 20
2012	Apr 21	Sep 23	Apr 12	Sep 23
2011	May 4	Sep 15	May 4	Oct 21
2010	May 9	Oct 3	May 9	Oct 3
2009	May 17	Oct 9	Apr 11	Oct 10
2008	Apr 29	Oct 4	Apr 29	Oct 16
2007	Apr 16	Sep 15	Apr 14	Oct 23
2006	May 6	Sep 20	Apr 9	Oct 12
2005	May 16	Oct 8	May 4	Oct 25
2004	May 15	Oct 2	May 3	Oct 5
2003	Apr 10	Sep 29	Apr 10	Sep 30
2002	Apr 26	Oct 5	Apr 25	Oct 16
2001	Apr 24	Oct 6	Apr 24	Oct 7
2000	Apr 22	Sep 21	Apr 12	Sep 25
1999	May 9	Sep 21	Mar 27	Oct 4
1998	Apr 17	Oct 8	Mar 24	Oct 22
1997	May 16	Oct 14	May 13	Oct 20
1996	May 13	Oct 3	Apr 23	Oct 8
1995	Apr 27	Sep 22	Apr 5	Oct 16
1994	May 2	Oct 10	Apr 7	Oct 10
1993	Apr 21	Sep 29	Apr 21	Oct 2
1992	May 6	Sep 29	Apr 13	Sep 29
1991	Apr 24	Sep 19	Apr 10	Sep 20
1990	May 2	Oct 10	Apr 18	Oct 10
1989	May 7	Sep 23	May 7	Sep 23
1988	Apr 29	Oct 3	Apr 21	Oct 4
1987	Apr 6	Oct 3	Apr 4	Oct 3
1986	Apr 22	Oct 6	Apr 22	Nov 2
1985	Apr 15	Oct 1	Apr 9	Nov 3
1984	Apr 30	Sep 25	Mar 31	Sep 26
1983	May 8	Sep 23	Apr 20	Sep 23
1982	Apr 22	Oct 16	Apr 11	Oct 21
1981	May 10	Oct 2	Apr 15	Oct 19
1980	Apr 24	Sep 26	Apr 14	Oct 12
1979	Apr 30	Oct 5	Apr 10	Oct 13
1978	May 2	Oct 8	Apr 21	Oct 8
1977	Apr 8	Oct 12	Apr 6	Oct 16
1976	May 4	Sep 24	Apr 12	Oct 6
1975	Apr 22	Sep 26	Apr 12	Oct 2
1974	May 6	Sep 22	Apr 8	Sep 22
1973	May 3	Oct 30	Apr 16	Oct 30
1972	Apr 26	Sep 30	Apr 8	Oct 15
1971	May 3	Oct 7	Apr 14	Nov 4
1970	May 2	Oct 4	Apr 10	Oct 16
1969	May 12	Oct 14	Apr 29	Oct 14
1968	May 5	Oct 4	Apr 24	Oct 4
1967	May 6	Sep 28	May 6	Sep 29
1966	May 11	Oct 1	May 10	Oct 17
1965	Apr 28	Oct 13	Apr 19	Oct 13
1964	Apr 15	Sep 28	Apr 10	Oct 9
1963	May 23	Oct 28	Apr 24	Oct 29
1962	Apr 20	Oct 21	Apr 16	Oct 24
1961	May 3	Sep 28	Apr 16	Sep 28
1960	May 12	Oct 19	Apr 18	Oct 19
1959	Apr 22	Oct 12	Apr 21	Oct 12
1958	Apr 29	Oct 1	Apr 29	Oct 29
1957	May 5	Oct 10	Apr 14	Oct 19
1956	May 16	Sep 30	Apr 30	Oct 9
1955	Apr 7	Sep 12	Apr 7	Oct 24
1954	May 20	Oct 18	Apr 12	Oct 30
1953	May 13	Oct 7	Apr 27	Oct 27
1952	Apr 16	Oct 3	Apr 11	Oct 5
1951	Apr 26	Sep 28	Apr 19	Oct 27

"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.