Frost history / Napa Co Ap, CA
Napa Co Ap, CA: frost dates by year
Last spring and first fall frost at NOAA station USW00093227, 1998 to 2024, measured from daily minimum temperatures.
Elevation 14 ft, 38.210, -122.285. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | Mar 28 | Nov 17 |
| Earliest | Jan 1 (2016) | Oct 27 (2011) |
| Latest | May 23 (2010) | Dec 10 (2021) |
| Trend | 14.7 days earlier per decade | little change (less than half a day per decade) |
| Years with data | 26 | 27 |
At 28°F (hard freeze) the median last spring date is Feb 9 and the median first fall date is Nov 29.
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 | Jan 12 | Nov 19 | Jan 7 | none |
| 2023 | Mar 1 | Nov 25 | none | none |
| 2022 | May 11 | Nov 3 | Feb 25 | none |
| 2021 | Mar 21 | Dec 10 | Jan 26 | none |
| 2020 | Mar 27 | Nov 10 | Feb 3 | none |
| 2019 | Feb 23 | Oct 31 | Jan 2 | Nov 29 |
| 2018 | Mar 25 | Nov 9 | Feb 25 | none |
| 2017 | Feb 28 | Nov 18 | Jan 6 | Dec 14 |
| 2016 | Jan 1 | Dec 6 | Jan 1 | Dec 18 |
| 2015 | Apr 4 | Nov 11 | Jan 3 | Nov 29 |
| 2014 | Feb 4 | Nov 17 | Feb 4 | none |
| 2013 | Mar 9 | Nov 4 | Feb 22 | Dec 4 |
| 2012 | Apr 6 | Nov 10 | Feb 28 | Dec 19 |
| 2011 | Apr 9 | Oct 27 | Feb 27 | Dec 6 |
| 2010 | May 23 | Nov 23 | none | Nov 24 |
| 2009 | Apr 30 | Nov 13 | Mar 10 | Nov 15 |
| 2008 | Apr 30 | Dec 8 | Apr 24 | Dec 9 |
| 2007 | Mar 29 | Nov 20 | Jan 25 | Nov 21 |
| 2006 | Mar 13 | Nov 10 | Feb 20 | Nov 24 |
| 2005 | Apr 14 | Nov 19 | none | Nov 27 |
| 2004 | Apr 17 | Nov 20 | Jan 5 | Nov 29 |
| 2003 | Apr 5 | Nov 1 | Feb 9 | Nov 21 |
| 2002 | Mar 19 | Oct 31 | Mar 8 | none |
| 2001 | Apr 15 | Nov 26 | Apr 3 | none |
| 2000 | Jan 28 | Nov 9 | Jan 7 | Nov 10 |
| 1999 | Apr 28 | Dec 4 | Feb 10 | Dec 4 |
| 1998 | no data | Nov 19 | no data | Dec 5 |
"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.