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

Planting zone for San Jose, CA

San Jose, CA is in USDA zones 9b to 10a across its 55 ZIP codes.

San Jose on the zone map

Outlined: its 28 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.

Zones9b–10a25 to 35 °F

ZIP codes55

Last frostrare

First frostrare

Growing seasonall year

9b 48 ZIPs 10a 7 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for San Jose, 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

A 32 °F frost doesn't happen here in most winters. At the nearest station (NOAA station San Jose, CA, elevation 66 ft) the median growing season is 362 days. When frost does come, it is a midwinter night or two; cover tender plants when a freeze is forecast.

Frost data: NOAA NCEI U.S. Climate Normals 1991–2020.

When spring arrived in 2026

In 2026, spring leaf-out near 95172 came on Jan 26 — about the same time as the 1991–2020 average (Jan 27).

average
Jan 272026
Jan 26

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 Jose, CA

The soil mapped at the center of ZIP 95172 is Elpaloalto — slightly decomposed plant material, well drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureSlightly decomposed plant materialtop layer

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

DrainageWell drainednatural drainage class

Organic matter75%high

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Urban land-Elpaloalto complex, 0 to 2 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 95172; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in San Jose, CA

Summer high83 °Faverage high, August

Winter low43 °Faverage low, January

Hot days21days a year at 90 °F or more

Freezing nights2nights a year at 32 °F or less

Growing degree days4,309base 50 °F — the season’s usable heat

Longest day14 h 44 mindaylight on June 21

Shortest day9 h 35 mindaylight on December 21

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

Precipitation16.1 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: San Jose, CA (within 1 mile); precipitation: San Jose, CA (within 1 mile). Daylight is calculated from latitude.