Ottawa 5SW, IL: frost dates by year

Last spring and first fall frost at NOAA station USC00116526, 1951 to 2025, measured from daily minimum temperatures.

Elevation 525 ft, 41.328, -88.911. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	Apr 21	Oct 19
Earliest	Mar 23 (2017)	Sep 23 (1974)
Latest	May 28 (1992)	Nov 12 (2016)
Trend	little change (less than half a day per decade)	little change (less than half a day per decade)
Years with data	74	74

At 28°F (hard freeze) the median last spring date is Apr 8 and the median first fall date is Nov 1.

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

"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.