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

Planting zone for 94580 — San Lorenzo, CA

ZIP code 94580 (San Lorenzo, Alameda County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.

Where ZIP 94580 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 San Lorenzo, 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 Hayward Air Terminal, CA — 2 miles away, elevation 43 ft) the median growing season is 365 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 94580 came on Jan 26 — about the same time as 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 San Lorenzo, CA

The soil mapped at the center of ZIP 94580 is Clear Lake — clay, poorly drained.

TextureClayholds water and nutrients; slow to drain and warm up
pH7.0neutral; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter2%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Clear Lake clay, drained, 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 94580; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in San Lorenzo, CA

Summer high77 °Faverage high, September
Winter low43 °Faverage low, January
Hot days9days a year at 90 °F or more
Freezing nights1nights a year at 32 °F or less
Growing degree days3,627base 50 °F — the season’s usable heat
Longest day14 h 46 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
Precipitation16 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°32 °FJanuary: average high 59 °F, low 43 °F 59°43° JanFebruary: average high 62 °F, low 45 °F 62°45° FebMarch: average high 64 °F, low 47 °F 64°47° MarApril: average high 67 °F, low 50 °F 67°50° AprMay: average high 69 °F, low 52 °F 69°52° MayJune: average high 74 °F, low 55 °F 74°55° JunJuly: average high 75 °F, low 57 °F 75°57° JulAugust: average high 76 °F, low 58 °F 76°58° AugSeptember: average high 77 °F, low 58 °F 77°58° SepOctober: average high 74 °F, low 54 °F 74°54° OctNovember: average high 65 °F, low 47 °F 65°47° NovDecember: average high 59 °F, low 43 °F 59°43° Dec

Precipitation by month inches

0″1″2″3″4″January: 2.91 in precipitation 2.9 JanFebruary: 3.11 in precipitation 3.1 FebMarch: 2.35 in precipitation 2.4 MarApril: 1.20 in precipitation 1.2 AprMay: 0.58 in precipitation 0.6 MayJune: 0.15 in precipitation 0.1 JunJuly: 0.00 in precipitation 0.0 JulAugust: 0.10 in precipitation 0.1 AugSeptember: 0.08 in precipitation 0.1 SepOctober: 0.81 in precipitation 0.8 OctNovember: 1.51 in precipitation 1.5 NovDecember: 3.20 in precipitation 3.2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Hayward Air Terminal, CA (2 mi away); precipitation: Hayward Air Terminal, CA (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

1 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

9457910a
San Leandro, CA · 1 mi
9457810a
San Leandro, CA · 2 mi
9454110a
Hayward, CA · 3 mi
9454310a
Hayward, CA · 3 mi
9457710a
San Leandro, CA · 3 mi
9454510a
Hayward, CA · 3 mi
9460310a
Oakland, CA · 5 mi
945469b
Castro Valley, CA · 5 mi

California planting zones →

Questions about 94580

What planting zone is ZIP code 94580?

ZIP code 94580 (San Lorenzo, 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 94580 get?

About 16 inches of precipitation a year (NOAA 1991–2020 normals, Hayward Air Terminal station).

How hot do summers get in San Lorenzo, CA?

The average high peaks at 77 °F in September, with about 9 days a year at 90 °F or more.

What kind of soil does 94580 have?

The USDA soil survey maps Clear Lake at the center of ZIP 94580: clay, poorly drained, pH about 7.0 (neutral).

Did spring come early in San Lorenzo, CA in 2026?

Spring leaf-out near 94580 came on Jan 26 in 2026, about the same as the 1991–2020 average (Jan 27), according to the USA National Phenology Network Spring Index.

What kind of onions grow in San Lorenzo, CA?

Intermediate onions: the longest day near 94580 is 14 h 46 min, so day-neutral types bulb best; long-day varieties may not bulb fully.