Denison, IA: frost dates by year

Last spring and first fall frost at NOAA station USC00132171, 1951 to 2024, measured from daily minimum temperatures.

Elevation 1,401 ft, 42.036, -95.329. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	Apr 28	Oct 7
Earliest	Apr 4 (1998)	Sep 15 (2007)
Latest	Jun 3 (1969)	Nov 3 (1998)
Trend	1.2 days earlier per decade	0.9 days later per decade
Years with data	72	73

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