Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for Santa Rosa, CA

Santa Rosa, CA is in USDA zones 9a to 9b across its 8 ZIP codes. The median last spring frost is February 25 and the first fall frost December 1.

Santa Rosa on the zone map

Outlined: its 6 ZIP code areas · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zones9a–9b20 to 30 °F
ZIP codes8
Last frostFeb 25
First frostDec 1
Growing season279 days

9a 5 ZIPs   9b 3 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Santa Rosa, CA…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Santa Rosa, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 25median — 50% chance of a later frost
Safe for tender plantsMarch 29only 10% chance of frost after
First fall frostDecember 1median — 10% chance by Nov 10
Growing season279 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 20 and returns around December 16.

From the NOAA station Santa Rosa, CA, elevation 167 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in Santa Rosa

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 14 – Jan 28
SpinachSow outdoors · Jan 14 – Feb 4
Broccoli, cabbageStart indoors · Dec 17 – Dec 31
Broccoli, cabbageTransplant · Feb 4 – Feb 18
Onion setsPlant outdoors · Jan 28 – Feb 11
PotatoesPlant outdoors · Feb 4 – Feb 18
LettuceSow outdoors · Jan 28 – Feb 11
Carrots, beetsSow outdoors · Feb 4 – Feb 18
TomatoesStart indoors · Dec 31 – Jan 14
TomatoesTransplant · Mar 4 – Mar 18
Peppers, eggplantStart indoors · Dec 17 – Dec 31
Peppers, eggplantTransplant · Mar 11 – Mar 25
BeansSow outdoors · Mar 4 – Mar 18
Sweet cornSow outdoors · Mar 4 – Mar 18
Cucumbers, squashSow outdoors · Mar 4 – Mar 18
Fall lettuce, spinachSow outdoors · Oct 6 – Oct 20
GarlicPlant cloves · Nov 17 – Dec 22
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 25) and first fall frost (Dec 1) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 95402 came on Jan 29 — about the same time as the 1991–2020 average (Jan 30).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Soil in Santa Rosa, CA

The soil mapped at the center of ZIP 95402 is Yolo — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH7.0neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.4%moderate
Hydrologic groupBwater soaks in moderately
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Yolo silt loam, 0 to 5 percent slopes, MLRA 14.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 95402; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Santa Rosa, CA

Summer high84 °Faverage high, September
Winter low38 °Faverage low, January
Hot days26days a year at 90 °F or more
Freezing nights15nights a year at 32 °F or less
Growing degree days3,509base 50 °F — the season’s usable heat
Longest day14 h 51 mindaylight on June 21
Shortest day9 h 29 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation31.5 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°32 °FJanuary: average high 60 °F, low 38 °F 60°38° JanFebruary: average high 64 °F, low 40 °F 64°40° FebMarch: average high 67 °F, low 42 °F 67°42° MarApril: average high 71 °F, low 44 °F 71°44° AprMay: average high 75 °F, low 48 °F 75°48° MayJune: average high 80 °F, low 51 °F 80°51° JunJuly: average high 82 °F, low 52 °F 82°52° JulAugust: average high 83 °F, low 53 °F 83°53° AugSeptember: average high 84 °F, low 51 °F 84°51° SepOctober: average high 79 °F, low 48 °F 79°48° OctNovember: average high 67 °F, low 42 °F 67°42° NovDecember: average high 59 °F, low 38 °F 59°38° Dec

Precipitation by month inches

0″2″4″6″January: 5.78 in precipitation 5.8 JanFebruary: 6.39 in precipitation 6.4 FebMarch: 4.26 in precipitation 4.3 MarApril: 1.98 in precipitation 2.0 AprMay: 1.28 in precipitation 1.3 MayJune: 0.29 in precipitation 0.3 JunJuly: 0.01 in precipitation 0.0 JulAugust: 0.04 in precipitation 0.0 AugSeptember: 0.15 in precipitation 0.1 SepOctober: 1.63 in precipitation 1.6 OctNovember: 3.25 in precipitation 3.3 NovDecember: 6.47 in precipitation 6.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Santa Rosa, CA (within 1 mile); precipitation: Santa Rosa, CA (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Santa Rosa

954019a
20 to 25 °F
954029b
25 to 30 °F
954039a
20 to 25 °F
954049b
25 to 30 °F
954059a
20 to 25 °F
954069a
20 to 25 °F
954079a
20 to 25 °F
954099b
25 to 30 °F

California planting zones →

Questions about Santa Rosa

What planting zone is Santa Rosa, CA?

Santa Rosa, CA is in USDA hardiness zones 9a to 9b on the 2023 map (9a: 20 to 25 °F; 9b: 25 to 30 °F).

When is the last frost in Santa Rosa, CA?

The median last spring frost is February 25 and the median first fall frost is December 1 (NOAA 1991–2020 normals, Santa Rosa station).

When can I plant a garden in Santa Rosa, CA?

Cool-season crops like peas and spinach go in around Jan 14 – Feb 4; tomatoes, peppers, beans and squash after about Mar 4, once frost risk has passed.

What kind of onions grow in Santa Rosa, CA?

Intermediate onions: the longest day is 14 h 51 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

How much rain and snow does Santa Rosa, CA get?

About 31.5 inches of precipitation a year (NOAA 1991–2020 normals).