When to plant in Suisun, CA

Planting dates worked out from Suisun's own frost records, not a generic zone chart.

Frost is rare in Suisun: in 8 of the last 29 springs there was none at all. Frost dates matter less here than heat, so the planting table below is left out.

Safe to plant out

Mar 10

1 year in 10 has a later frost

Average last frost

Jan 28

about a 50% chance of a later one

Average first fall frost

Dec 11

1 year in 10 by Nov 25

Frost-free days

330

median, 1991–2020

Station used: Fairfield · 4.6 km away · station 12 m, town 2 m. How we match towns to stations

Suisun's weather over time

How the growing season has shifted here, year by year, from the station's own records.

Each year's last spring frostLong-term trend

See the data as a table

Year	Last spring frost
1951	Mar 11
1952	Mar 13
1955	Mar 21
1958	Apr 25
1959	Feb 13
1960	Feb 24
1961	Jan 21
1962	Mar 13
1963	Jan 25
1964	Mar 25
1965	Feb 12
1966	Mar 4
1967	Apr 1
1968	Apr 29
1969	Feb 3
1970	Jan 8
1971	Mar 6
1972	Feb 3
1973	Jan 27
1974	Mar 9
1975	Feb 23
1976	Mar 6
1977	Mar 14
1979	Mar 1
1980	Feb 1
1981	Mar 7
1982	Feb 11
1983	Jan 21
1984	Feb 23
1985	Mar 23
1986	Apr 13
1987	Jan 22
1988	Feb 4
1989	Feb 14
1990	Feb 20
1991	Jan 5
1992	Jan 15
1993	Jan 26
1994	Feb 12
1997	Jan 15
1999	Feb 12
2000	Jan 6
2001	Jan 18
2002	Jan 31
2004	Jan 23
2006	Mar 12
2007	Feb 3
2009	Mar 10
2010	Apr 9
2011	Jun 9
2012	Jan 19
2013	Jan 22
2015	Jan 7
2017	Jan 6
2018	Feb 24
2019	Feb 11
2021	Jan 26
2022	Feb 25
2025	Jan 29

Each year's frost-free daysLong-term trend

See the data as a table

Year	Frost-free days
1951	271
1955	248
1958	201
1959	293
1960	285
1961	299
1962	260
1963	318
1964	236
1965	289
1966	264
1967	243
1968	217
1969	289
1970	337
1971	278
1972	292
1973	337
1974	283
1975	270
1977	291
1978	314
1979	264
1980	282
1981	264
1982	302
1983	311
1984	250
1985	230
1986	238
1987	331
1988	299
1989	287
1990	296
1992	330
1993	302
1996	351
1997	341
1998	338
2000	353
2003	325
2004	309
2005	348
2006	262
2007	300
2008	349
2009	270
2010	230
2011	118
2012	334
2014	363
2015	325
2016	350
2017	349
2018	309
2019	322
2020	353
2021	325
2022	279
2023	363
2024	363

Each year's average temperature, April to SeptemberLong-term trend

See the data as a table

Year	Growing-season temperature
1951	19.1 °C
1952	19.6 °C
1956	19.3 °C
1958	20.3 °C
1959	20.3 °C
1960	20.4 °C
1961	20.2 °C
1962	19.6 °C
1963	19.2 °C
1964	19.4 °C
1965	18.9 °C
1966	19.7 °C
1967	19.5 °C
1968	19.8 °C
1969	20.2 °C
1970	19.7 °C
1971	19.3 °C
1972	19.2 °C
1973	19.7 °C
1974	19.1 °C
1975	18.4 °C
1977	18.8 °C
1978	19.4 °C
1979	20.3 °C
1980	19.4 °C
1981	21.4 °C
1982	20.1 °C
1984	22.0 °C
1985	20.3 °C
1986	19.2 °C
1987	19.9 °C
1988	19.9 °C
1989	19.8 °C
1990	20.6 °C
1991	19.2 °C
1992	21.2 °C
1993	20.6 °C
1994	20.4 °C
1996	21.2 °C
1997	21.4 °C
1998	19.7 °C
1999	19.5 °C
2000	20.5 °C
2001	20.7 °C
2002	20.6 °C
2003	20.4 °C
2004	20.9 °C
2005	19.5 °C
2006	20.6 °C
2007	20.2 °C
2008	20.6 °C
2009	20.3 °C
2010	18.5 °C
2011	18.8 °C
2012	20.1 °C
2014	21.2 °C
2015	21.0 °C
2016	20.8 °C
2017	21.2 °C
2018	20.4 °C
2019	21.0 °C
2020	22.0 °C
2021	21.4 °C
2022	21.4 °C
2023	20.1 °C
2024	22.4 °C
2025	21.1 °C

What this means for you: Since 1951, Suisun's last spring frost has come about 4 days earlier per decade, on average. The frost-free season has grown by about 9 days per decade. Year-to-year swings are large, so keep using the safe date rather than the trend.

Source: daily records from Fairfield (NOAA GHCN-Daily). Years with too many missing days are left out.

Nearby towns

Fairfield Green Valley Vacaville American Canyon Hartley Napa