Frost history / Saint Helena, CA
Saint Helena, CA: frost dates by year
Last spring and first fall frost at NOAA station USC00047643, 1951 to 2020, measured from daily minimum temperatures.
Elevation 225 ft, 38.507, -122.471. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | Mar 17 | Nov 23 |
| Earliest | Jan 1 (2016) | Oct 17 (1971) |
| Latest | Apr 29 (1952) | Dec 27 (2003) |
| Trend | 9.6 days earlier per decade | 3.3 days later per decade |
| Years with data | 56, 1 with no freeze | 59, 3 with no freeze |
At 28°F (hard freeze) the median last spring date is Feb 6 and the median first fall date is Dec 6.
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 |
|---|---|---|---|---|
| 2020 | Feb 10 | no data | Feb 9 | no data |
| 2018 | Mar 17 | Nov 18 | none | none |
| 2017 | Apr 11 | Dec 22 | none | none |
| 2016 | Jan 1 | Dec 7 | none | Dec 20 |
| 2015 | Jan 30 | Nov 29 | none | Nov 29 |
| 2014 | Feb 5 | none | none | none |
| 2013 | Feb 9 | Dec 5 | Jan 13 | Dec 5 |
| 2012 | Feb 27 | no data | Jan 17 | no data |
| 2011 | Mar 1 | Nov 29 | Feb 26 | Nov 29 |
| 2010 | none | Nov 24 | none | none |
| 2009 | Mar 10 | no data | Jan 4 | no data |
| 2008 | Jan 29 | Dec 7 | none | Dec 14 |
| 2007 | Feb 28 | Dec 1 | Jan 16 | none |
| 2006 | Mar 13 | Nov 29 | none | none |
| 2005 | no data | Nov 27 | no data | none |
| 2004 | no data | Nov 30 | no data | none |
| 2003 | Feb 28 | Dec 27 | none | none |
| 2002 | Mar 8 | Nov 2 | Jan 30 | none |
| 2001 | Feb 1 | none | Jan 5 | none |
| 2000 | Jan 7 | Nov 12 | none | Dec 20 |
| 1999 | Apr 9 | no data | none | no data |
| 1998 | no data | Dec 4 | no data | Dec 21 |
| 1997 | Jan 15 | Dec 9 | none | none |
| 1996 | Feb 27 | Dec 3 | none | none |
| 1995 | Feb 14 | none | none | none |
| 1994 | Mar 22 | Nov 14 | none | Dec 9 |
| 1993 | Jan 31 | Nov 15 | Jan 10 | Nov 24 |
| 1992 | Feb 1 | no data | Jan 23 | no data |
| 1991 | Jan 31 | Nov 15 | Jan 29 | Dec 15 |
| 1990 | no data | Nov 26 | no data | Dec 19 |
| 1989 | Mar 2 | Dec 11 | Feb 7 | Dec 16 |
| 1988 | no data | Dec 20 | no data | Dec 25 |
| 1986 | no data | Nov 29 | no data | none |
| 1985 | no data | Nov 11 | no data | Nov 12 |
| 1984 | Feb 13 | no data | Jan 12 | no data |
| 1983 | Feb 3 | Dec 3 | Jan 19 | none |
| 1982 | Apr 7 | no data | Feb 11 | no data |
| 1981 | no data | Dec 22 | no data | none |
| 1978 | Feb 11 | Nov 12 | none | Nov 12 |
| 1977 | Mar 31 | Nov 20 | Mar 14 | Nov 20 |
| 1976 | Apr 2 | Nov 29 | Mar 6 | Nov 29 |
| 1975 | Apr 17 | Nov 9 | Jan 31 | Nov 29 |
| 1974 | Mar 9 | Nov 23 | Jan 10 | Dec 24 |
| 1973 | Mar 22 | Nov 3 | Jan 27 | none |
| 1972 | Apr 13 | Nov 23 | Feb 1 | Dec 5 |
| 1971 | Apr 21 | Oct 17 | Mar 6 | Nov 7 |
| 1970 | Apr 28 | Oct 29 | Jan 6 | Dec 20 |
| 1969 | Apr 3 | Nov 17 | Mar 11 | Nov 30 |
| 1968 | Mar 12 | Nov 27 | Jan 28 | Dec 4 |
| 1967 | Apr 28 | Nov 27 | Mar 5 | Dec 1 |
| 1966 | Mar 17 | Nov 23 | Mar 17 | Dec 26 |
| 1965 | Apr 7 | Nov 26 | Jan 8 | Dec 15 |
| 1964 | Apr 25 | Nov 14 | Feb 27 | Nov 17 |
| 1963 | Apr 21 | Nov 22 | Mar 17 | Dec 11 |
| 1962 | Mar 24 | Nov 29 | Mar 13 | Dec 25 |
| 1961 | no data | Nov 9 | no data | Nov 17 |
| 1960 | Apr 24 | Nov 23 | Feb 27 | Dec 9 |
| 1959 | no data | Nov 12 | no data | Dec 6 |
| 1958 | Mar 18 | Nov 12 | Jan 7 | Nov 17 |
| 1957 | Mar 24 | Nov 4 | Feb 5 | none |
| 1956 | Apr 3 | Oct 24 | Feb 18 | Dec 7 |
| 1955 | Apr 27 | Nov 12 | Mar 17 | none |
| 1954 | Mar 18 | Nov 30 | Mar 13 | Nov 30 |
| 1953 | Apr 12 | Nov 18 | Apr 8 | Dec 23 |
| 1952 | Apr 29 | Nov 2 | Mar 20 | Nov 25 |
| 1951 | Apr 1 | Nov 23 | Mar 10 | Dec 9 |
"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.