Planting zone for 94083 — South San Francisco, CA
ZIP code 94083 (South San Francisco, San Mateo County) is in USDA zone 10b: the coldest winter night averages 35 to 40 °F.
Where ZIP 94083 is
tap the map for the zone at any spot · scroll or pinch to zoomNot 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.
Was 10a on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 10b means →
Frost forecast — next 7 nights
live from the National Weather ServiceLoading the forecast for South San Francisco, 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 Francisco Intl Airport, CA — 3 miles away, elevation 7 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 94083 came on Jan 23 — 3 days earlier than the 1991–2020 average (Jan 26).
Jan 262026
Jan 23
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 South San Francisco, CA
The center of ZIP 94083 is mapped as Urban land: built-over ground without natural soil data. Garden soil here is usually imported or disturbed — test before you plant.
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 94083; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.
Climate in South San Francisco, CA
Average high and low, by month
Precipitation by month inches
NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: San Francisco Intl Airport, CA (3 mi away); precipitation: San Francisco Intl Airport, CA (3 mi away). Daylight is calculated from latitude.
Nearby ZIP codes
7 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.
All 2 ZIP codes in South San Francisco → · California planting zones →
Questions about 94083
What planting zone is ZIP code 94083?
ZIP code 94083 (South San Francisco, CA) is in USDA hardiness zone 10b on the 2023 map: the coldest night of an average winter reaches 35 to 40 °F (1.7 to 4.4 °C).
How much rain and snow does 94083 get?
About 19.6 inches of precipitation a year (NOAA 1991–2020 normals, San Francisco Intl Airport station).
How hot do summers get in South San Francisco, CA?
The average high peaks at 75 °F in September, with about 4 days a year at 90 °F or more.
Did spring come early in South San Francisco, CA in 2026?
Spring leaf-out near 94083 came on Jan 23 in 2026, 3 days earlier than the 1991–2020 average (Jan 26), according to the USA National Phenology Network Spring Index.
What kind of onions grow in South San Francisco, CA?
Intermediate onions: the longest day near 94083 is 14 h 46 min, so day-neutral types bulb best; long-day varieties may not bulb fully.
Did the zone for 94083 change?
Yes. The 2012 USDA map put 94083 in zone 10a; the 2023 map puts it in zone 10b. The newer map uses 1991–2020 data and more weather stations.