Frost history / Trinity Rvr Hatchery, CA
Trinity Rvr Hatchery, CA: frost dates by year
Last spring and first fall frost at NOAA station USC00049026, 1975 to 2025, measured from daily minimum temperatures.
Elevation 1,861 ft, 40.726, -122.795. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | Apr 22 | Oct 22 |
| Earliest | Mar 19 (2025) | Sep 19 (1978) |
| Latest | May 29 (2011) | Dec 3 (2025) |
| Trend | 5.3 days earlier per decade | little change (less than half a day per decade) |
| Years with data | 48 | 49 |
At 28°F (hard freeze) the median last spring date is Mar 29 and the median first fall date is Nov 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 |
|---|---|---|---|---|
| 2025 | Mar 19 | Dec 3 | Feb 13 | none |
| 2024 | Apr 7 | Oct 18 | Mar 3 | Dec 10 |
| 2023 | Apr 20 | Oct 26 | Apr 14 | Oct 27 |
| 2022 | May 3 | Oct 23 | Mar 12 | Nov 16 |
| 2021 | Apr 1 | Oct 12 | Mar 31 | Oct 12 |
| 2020 | Apr 15 | Oct 23 | Mar 27 | Oct 26 |
| 2019 | Mar 20 | Oct 9 | Mar 16 | Oct 10 |
| 2018 | Apr 18 | Oct 15 | Mar 24 | Nov 6 |
| 2017 | Apr 15 | Oct 2 | Apr 1 | Oct 12 |
| 2016 | Apr 26 | Nov 18 | Mar 30 | Dec 6 |
| 2015 | Apr 16 | Nov 4 | Mar 5 | Nov 16 |
| 2014 | Mar 25 | Nov 17 | Mar 19 | Dec 29 |
| 2013 | no data | Sep 27 | no data | Nov 3 |
| 2012 | Apr 14 | Nov 10 | Apr 6 | Nov 10 |
| 2011 | May 29 | Oct 26 | Apr 30 | Oct 26 |
| 2010 | May 22 | Oct 27 | Mar 11 | Nov 24 |
| 2009 | Apr 29 | Sep 30 | Apr 15 | Oct 28 |
| 2008 | Apr 30 | Oct 10 | Apr 21 | Oct 11 |
| 2007 | Apr 20 | Oct 5 | Mar 29 | Oct 6 |
| 2006 | Apr 22 | Oct 18 | Mar 20 | Oct 25 |
| 2005 | Apr 19 | Oct 4 | Mar 15 | Nov 27 |
| 2004 | Apr 22 | Sep 21 | Feb 13 | Nov 20 |
| 2003 | Apr 5 | Oct 13 | Feb 27 | Nov 1 |
| 2002 | May 8 | Oct 2 | Mar 19 | Oct 30 |
| 2001 | Apr 15 | Oct 24 | Apr 10 | Dec 10 |
| 2000 | May 12 | Oct 22 | Mar 21 | Nov 11 |
| 1999 | May 15 | Oct 17 | Apr 28 | Dec 22 |
| 1998 | Apr 17 | Oct 11 | Apr 12 | Dec 6 |
| 1997 | May 1 | Oct 24 | Apr 5 | Oct 25 |
| 1996 | Apr 22 | Oct 16 | Mar 26 | Oct 21 |
| 1995 | Apr 22 | Oct 12 | Apr 19 | Oct 23 |
| 1994 | Apr 7 | Oct 16 | Mar 23 | Oct 31 |
| 1993 | no data | Nov 1 | no data | Nov 6 |
| 1992 | Apr 7 | Nov 9 | Feb 5 | Nov 9 |
| 1991 | May 10 | Oct 23 | Apr 12 | Oct 30 |
| 1990 | Apr 29 | Oct 7 | Mar 14 | Oct 18 |
| 1989 | Mar 27 | Oct 29 | Mar 4 | Oct 29 |
| 1988 | no data | Nov 18 | no data | Nov 21 |
| 1987 | May 22 | Nov 14 | Apr 19 | Nov 15 |
| 1986 | May 22 | no data | Feb 11 | no data |
| 1985 | May 17 | no data | Mar 30 | no data |
| 1984 | Apr 28 | Sep 25 | Apr 26 | Nov 22 |
| 1983 | May 11 | Nov 7 | May 11 | Dec 20 |
| 1982 | May 9 | Nov 2 | Apr 16 | Nov 14 |
| 1981 | May 16 | Oct 13 | Mar 6 | none |
| 1980 | May 11 | Oct 16 | Apr 7 | Nov 13 |
| 1979 | Apr 19 | Nov 14 | Apr 18 | Nov 20 |
| 1978 | Apr 22 | Sep 19 | Feb 12 | Oct 30 |
| 1977 | May 17 | Nov 5 | Mar 31 | Nov 18 |
| 1976 | Apr 27 | Oct 27 | Apr 16 | Oct 27 |
| 1975 | May 5 | Oct 23 | Apr 18 | Oct 23 |
"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.