Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for Sebastopol, CA

Sebastopol, CA is in USDA zone 9a across its 2 ZIP codes. The median last spring frost is March 20 and the first fall frost November 13.

Sebastopol on the zone map

Outlined: its 1 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.

Zone9a20 to 25 °F

ZIP codes2

Last frostMar 20

First frostNov 13

Growing season240 days

9a 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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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 Sebastopol, CA

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMarch 20median — 50% chance of a later frost

Safe for tender plantsApril 19only 10% chance of frost after

First fall frostNovember 13median — 10% chance by Oct 26

Growing season240 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 1 and returns around December 3.

From the NOAA station Graton, CA, elevation 200 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 Sebastopol

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 6 – Feb 20

SpinachSow outdoors · Feb 6 – Feb 27

Broccoli, cabbageStart indoors · Jan 9 – Jan 23

Broccoli, cabbageTransplant · Feb 27 – Mar 13

Onion setsPlant outdoors · Feb 20 – Mar 6

PotatoesPlant outdoors · Feb 27 – Mar 13

LettuceSow outdoors · Feb 20 – Mar 6

Carrots, beetsSow outdoors · Feb 27 – Mar 13

TomatoesStart indoors · Jan 23 – Feb 6

TomatoesTransplant · Mar 27 – Apr 10

Peppers, eggplantStart indoors · Jan 9 – Jan 23

Peppers, eggplantTransplant · Apr 3 – Apr 17

BeansSow outdoors · Mar 27 – Apr 10

Sweet cornSow outdoors · Mar 27 – Apr 10

Cucumbers, squashSow outdoors · Mar 27 – Apr 10

Fall lettuce, spinachSow outdoors · Sep 18 – Oct 2

GarlicPlant cloves · Oct 30 – Dec 4

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 20) and first fall frost (Nov 13) 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 95473 came on Jan 30 — about the same time as the 1991–2020 average (Jan 31).

average
Jan 312026
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 Sebastopol, CA

The soil mapped at the center of ZIP 95473 is Sebastopol — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding

pH5.0strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Sebastopol sandy loam, 2 to 9 percent slopes.

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 95473; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sebastopol, CA

Summer high84 °Faverage high, August

Winter low37 °Faverage low, January

Hot days34days a year at 90 °F or more

Freezing nights43nights a year at 32 °F or less

Growing degree days3,190base 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

Precipitation36.8 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Graton, CA (3 mi away); precipitation: Sebastopol 1.1 Sse, CA (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Sebastopol

California planting zones →

Questions about Sebastopol

What planting zone is Sebastopol, CA?

Sebastopol, CA is in USDA hardiness zone 9a on the 2023 map (9a: 20 to 25 °F).

When is the last frost in Sebastopol, CA?

The median last spring frost is March 20 and the median first fall frost is November 13 (NOAA 1991–2020 normals, Graton station).

When can I plant a garden in Sebastopol, CA?

Cool-season crops like peas and spinach go in around Feb 6 – Feb 27; tomatoes, peppers, beans and squash after about Mar 27, once frost risk has passed.

What kind of onions grow in Sebastopol, 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 Sebastopol, CA get?

About 36.8 inches of precipitation a year (NOAA 1991–2020 normals).