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

Planting zone for 94502 — Alameda, CA

ZIP code 94502 (Alameda, Alameda County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.

Where ZIP 94502 is

Outlined: the ZIP code area · 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.

Zone10a30 to 35 °F
Coldest night−1.1 to 1.7 °C
Last frostrare
First frostrare
2012 zone10a

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 10a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Alameda, 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 Oakland Metro Intl Airport, CA — 2 miles away, elevation 7 ft) the median growing season is 356 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 94502 came on Jan 24 — 3 days earlier than the 1991–2020 average (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 Alameda, CA

The soil mapped at the center of ZIP 94502 is Xeropsamments — sand.

TextureSanddrains and warms fast; dries out and needs more feeding
pH7.5slightly alkaline; most vegetables like 6.0–7.0
Organic matter0.5%low — add compost
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Xeropsamments, fill.

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 94502; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Alameda, CA

Summer high74 °Faverage high, September
Winter low42 °Faverage low, January
Hot days6days a year at 90 °F or more
Freezing nights3nights a year at 32 °F or less
Growing degree days3,106base 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
Precipitation18.7 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°32 °FJanuary: average high 58 °F, low 42 °F 58°42° JanFebruary: average high 60 °F, low 45 °F 60°45° FebMarch: average high 63 °F, low 47 °F 63°47° MarApril: average high 66 °F, low 49 °F 66°49° AprMay: average high 68 °F, low 52 °F 68°52° MayJune: average high 71 °F, low 54 °F 71°54° JunJuly: average high 72 °F, low 56 °F 72°56° JulAugust: average high 72 °F, low 57 °F 72°57° AugSeptember: average high 74 °F, low 56 °F 74°56° SepOctober: average high 72 °F, low 51 °F 72°51° OctNovember: average high 64 °F, low 46 °F 64°46° NovDecember: average high 58 °F, low 42 °F 58°42° Dec

Precipitation by month inches

0″1″2″3″4″January: 3.42 in precipitation 3.4 JanFebruary: 3.51 in precipitation 3.5 FebMarch: 2.71 in precipitation 2.7 MarApril: 1.35 in precipitation 1.4 AprMay: 0.63 in precipitation 0.6 MayJune: 0.18 in precipitation 0.2 JunJuly: 0.00 in precipitation 0.0 JulAugust: 0.04 in precipitation 0.0 AugSeptember: 0.10 in precipitation 0.1 SepOctober: 0.88 in precipitation 0.9 OctNovember: 2.02 in precipitation 2.0 NovDecember: 3.84 in precipitation 3.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Oakland Metro Intl Airport, CA (2 mi away); precipitation: Oakland Metro Intl Airport, CA (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 10a.

9462110a
Oakland, CA · 2 mi
9461410a
Oakland, CA · 2 mi
9460110a
Oakland, CA · 3 mi
9450110a
Alameda, CA · 3 mi
9460310a
Oakland, CA · 3 mi
9460610a
Oakland, CA · 4 mi
9462210a
Oakland, CA · 4 mi
9457710a
San Leandro, CA · 4 mi

All 2 ZIP codes in Alameda → · California planting zones →

Questions about 94502

What planting zone is ZIP code 94502?

ZIP code 94502 (Alameda, CA) is in USDA hardiness zone 10a on the 2023 map: the coldest night of an average winter reaches 30 to 35 °F (−1.1 to 1.7 °C).

How much rain and snow does 94502 get?

About 18.7 inches of precipitation a year (NOAA 1991–2020 normals, Oakland Metro Intl Airport station).

How hot do summers get in Alameda, CA?

The average high peaks at 74 °F in September, with about 6 days a year at 90 °F or more.

What kind of soil does 94502 have?

The USDA soil survey maps Xeropsamments at the center of ZIP 94502: sand, pH about 7.5 (slightly alkaline).

Did spring come early in Alameda, CA in 2026?

Spring leaf-out near 94502 came on Jan 24 in 2026, 3 days earlier than the 1991–2020 average (Jan 27), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Alameda, CA?

Intermediate onions: the longest day near 94502 is 14 h 47 min, so day-neutral types bulb best; long-day varieties may not bulb fully.