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

Planting zone for San Ramon, CA

San Ramon, CA is in USDA zone 9b across its 2 ZIP codes. The median last spring frost is February 15 and the first fall frost December 2.

San Ramon on the zone map

Outlined: its 2 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.

Zone9b25 to 30 °F

ZIP codes2

Last frostFeb 15

First frostDec 2

Growing season292 days

9b 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 San Ramon, CA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostFebruary 15median — 50% chance of a later frost

Safe for tender plantsMarch 13only 10% chance of frost after

First fall frostDecember 2median — 10% chance by Nov 16

Growing season292 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 10 and returns around December 18.

From the NOAA station Livermore, CA, elevation 394 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 San Ramon

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 4 – Jan 18

SpinachSow outdoors · Jan 4 – Jan 25

Broccoli, cabbageStart indoors · Dec 7 – Dec 21

Broccoli, cabbageTransplant · Jan 25 – Feb 8

Onion setsPlant outdoors · Jan 18 – Feb 1

PotatoesPlant outdoors · Jan 25 – Feb 8

LettuceSow outdoors · Jan 18 – Feb 1

Carrots, beetsSow outdoors · Jan 25 – Feb 8

TomatoesStart indoors · Dec 21 – Jan 4

TomatoesTransplant · Feb 22 – Mar 8

Peppers, eggplantStart indoors · Dec 7 – Dec 21

Peppers, eggplantTransplant · Mar 1 – Mar 15

BeansSow outdoors · Feb 22 – Mar 8

Sweet cornSow outdoors · Feb 22 – Mar 8

Cucumbers, squashSow outdoors · Feb 22 – Mar 8

Fall lettuce, spinachSow outdoors · Oct 7 – Oct 21

GarlicPlant cloves · Nov 18 – Dec 23

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 15) and first fall frost (Dec 2) 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 94583 came on Jan 27 — 4 days earlier than the 1991–2020 average (Jan 31).

average
Jan 312026
Jan 27

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 San Ramon, CA

The soil mapped at the center of ZIP 94583 is Botella — clay loam, moderately well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up

pH6.0slightly acidic; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter4%moderate

Hydrologic groupCwater soaks in slowly

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Botella clay loam, 0 to 2 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 94583; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in San Ramon, CA

Summer high83 °Faverage high, July

Winter low41 °Faverage low, December

Hot days27days a year at 90 °F or more

Freezing nights19nights a year at 32 °F or less

Growing degree days3,645base 50 °F — the season’s usable heat

Longest day14 h 47 mindaylight on June 21

Shortest day9 h 33 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation21.8 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: Mt Diablo Junction, CA (8 mi away); precipitation: Castro Valley 0.4 Nne, CA (6 mi away). Daylight is calculated from latitude.

ZIP codes in San Ramon

California planting zones →

Questions about San Ramon

What planting zone is San Ramon, CA?

San Ramon, CA is in USDA hardiness zone 9b on the 2023 map (9b: 25 to 30 °F).

When is the last frost in San Ramon, CA?

The median last spring frost is February 15 and the median first fall frost is December 2 (NOAA 1991–2020 normals, Livermore station).

When can I plant a garden in San Ramon, CA?

Cool-season crops like peas and spinach go in around Jan 4 – Jan 25; tomatoes, peppers, beans and squash after about Feb 22, once frost risk has passed.

What kind of onions grow in San Ramon, CA?

Intermediate onions: the longest day is 14 h 47 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

How much rain and snow does San Ramon, CA get?

About 21.8 inches of precipitation a year (NOAA 1991–2020 normals).