Jefferson, IA: frost dates by year

Last spring and first fall frost at NOAA station USC00134228, 1951 to 2025, measured from daily minimum temperatures.

Elevation 1,055 ft, 42.010, -94.395. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	Apr 27	Oct 6
Earliest	Apr 7 (1955)	Sep 15 (2011)
Latest	May 15 (1983)	Oct 29 (1973)
Trend	0.7 days earlier per decade	little change (less than half a day per decade)
Years with data	68	68

At 28°F (hard freeze) the median last spring date is Apr 13 and the median first fall date is Oct 19.

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

"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.