Diablo Dam, WA: frost dates by year

Last spring and first fall frost at NOAA station USC00452157, 1951 to 2025, measured from daily minimum temperatures.

Elevation 891 ft, 48.714, -121.143. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	Apr 16	Nov 1
Earliest	Mar 15 (2024)	Sep 27 (1972)
Latest	May 14 (1964)	Nov 30 (2025)
Trend	2.0 days earlier per decade	little change (less than half a day per decade)
Years with data	69	73

At 28°F (hard freeze) the median last spring date is Mar 12 and the median first fall date is Nov 18.

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 14	Nov 30	Feb 16	Dec 27
2024	Mar 15	Nov 17	Mar 8	none
2023	Apr 20	Oct 26	Mar 28	Oct 28
2022	Apr 30	Nov 3	Mar 11	Nov 3
2021	Apr 15	Oct 12	Apr 12	Dec 17
2020	Apr 14	Oct 24	Mar 17	Oct 26
2019	Mar 27	Oct 10	Mar 11	Oct 29
2018	Apr 3	Nov 8	Mar 25	Dec 4
2017	Apr 16	Nov 3	Mar 7	Nov 7
2016	Mar 19	Nov 18	Feb 3	Dec 6
2015	Apr 5	Nov 10	Mar 5	Nov 21
2014	Apr 13	Nov 11	Mar 22	Nov 12
2013	Apr 22	Oct 30	Mar 25	Nov 20
2012	Apr 5	Nov 11	Mar 14	Nov 11
2011	Apr 23	Oct 26	Mar 23	Nov 6
2010	Apr 11	Nov 19	Feb 23	Nov 20
2009	no data	Oct 11	no data	Oct 11
2008	Apr 26	Oct 11	Apr 22	Nov 27
2007	Apr 21	Oct 31	Apr 3	Nov 22
2006	May 9	Oct 30	Mar 20	Oct 30
2005	Apr 5	Nov 8	Feb 22	Nov 28
2004	Apr 2	Oct 28	Jan 8	none
2003	Apr 2	Oct 31	Mar 10	Nov 3
2002	May 9	Oct 26	Mar 21	Oct 30
2001	Apr 15	Oct 29	Mar 4	Dec 12
2000	Apr 8	Nov 11	Mar 7	Nov 11
1999	May 10	Nov 1	Mar 11	none
1998	Apr 14	Nov 7	Mar 6	Dec 19
1996	May 9	Oct 17	Mar 28	Nov 19
1995	Apr 16	Oct 29	Mar 25	Oct 30
1994	Mar 25	Oct 31	Mar 24	Nov 6
1993	Apr 6	Nov 8	Mar 16	Nov 14
1992	Apr 9	Oct 15	Jan 21	Nov 24
1991	Apr 12	Oct 28	Mar 27	Oct 28
1990	Mar 31	Nov 6	Mar 12	Dec 19
1989	Apr 9	Oct 29	Mar 5	Dec 11
1988	Apr 9	Oct 28	Feb 3	Dec 15
1987	no data	Nov 17	no data	Nov 17
1986	Apr 24	Nov 8	Feb 22	Nov 9
1985	no data	Oct 8	no data	Nov 11
1984	Apr 27	no data	Feb 17	no data
1983	Apr 14	Nov 27	Feb 6	Nov 30
1982	May 5	Oct 19	Apr 24	Nov 10
1981	May 5	Nov 6	Feb 12	Nov 28
1980	Apr 11	Nov 11	Mar 7	Dec 4
1979	Apr 21	Nov 1	Mar 3	Nov 26
1978	Apr 7	Oct 26	Mar 4	Nov 11
1977	Apr 20	Nov 6	Jan 31	Nov 18
1976	Apr 23	Oct 22	Apr 2	Nov 27
1975	Apr 29	Oct 24	Apr 8	Nov 18
1974	Mar 23	Nov 4	Mar 15	Dec 23
1973	Apr 29	Nov 2	Feb 9	Nov 3
1972	May 1	Sep 27	Feb 10	Oct 30
1971	Apr 23	Oct 17	Mar 21	Oct 28
1970	Apr 28	Oct 27	Mar 10	Nov 21
1969	Apr 26	Oct 14	Mar 13	none
1968	Apr 22	Nov 1	Feb 17	Dec 6
1967	Apr 24	Nov 3	Mar 14	Nov 26
1966	no data	Oct 21	no data	Nov 11
1965	no data	Nov 23	no data	Dec 13
1964	May 14	Oct 27	Mar 20	Nov 29
1963	Apr 1	Nov 11	Mar 4	Nov 20
1962	May 5	Nov 23	Mar 13	Nov 29
1961	Apr 20	Oct 23	Mar 5	Nov 16
1960	Apr 22	Nov 7	Mar 13	Nov 27
1959	Apr 24	Nov 4	Feb 23	Nov 13
1958	Apr 6	Nov 13	Mar 8	Nov 15
1957	Apr 16	Nov 2	Mar 12	Dec 31
1956	Apr 15	Oct 28	Mar 13	Oct 28
1955	Apr 29	Nov 2	Mar 26	Nov 11
1954	May 1	Oct 24	May 1	Dec 1
1953	Apr 15	Nov 3	Mar 20	none
1952	May 5	Nov 2	Apr 8	Nov 25
1951	Apr 23	Oct 27	Apr 21	Oct 30

"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.