Planting zone for 94903 — San Rafael, CA
ZIP code 94903 (San Rafael, Marin County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F.
Where ZIP 94903 is
Outlined: the ZIP code area · 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 colder now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 9b means →
Frost forecast — next 7 nights
live from the National Weather ServiceLoading the forecast for San Rafael, 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 Rafael Civic Center, CA — 2 miles away, elevation 121 ft) the median growing season is 349 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 94903 came on Jan 29 — about the same time as the 1991–2020 average (Jan 29).
Jan 292026
Jan 29
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 Rafael, CA
The soil mapped at the center of ZIP 94903 is Tocaloma — loam, well drained.
Map unit: Tocaloma-Saurin association, extremely steep.
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 94903; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.
Climate in San Rafael, CA
Average high and low, by month
Precipitation by month inches
NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: San Rafael Civic Center, CA (2 mi away); precipitation: San Anselmo 2.0 Nnw, CA (within 1 mile). 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.
All 5 ZIP codes in San Rafael → · California planting zones →
Questions about 94903
What planting zone is ZIP code 94903?
ZIP code 94903 (San Rafael, CA) is in USDA hardiness zone 9b on the 2023 map: the coldest night of an average winter reaches 25 to 30 °F (−3.9 to −1.1 °C).
How much rain and snow does 94903 get?
About 36.3 inches of precipitation a year (NOAA 1991–2020 normals, San Anselmo 2.0 Nnw station).
How hot do summers get in San Rafael, CA?
The average high peaks at 81 °F in July, with about 20 days a year at 90 °F or more.
What kind of soil does 94903 have?
The USDA soil survey maps Tocaloma at the center of ZIP 94903: loam, well drained, pH about 6.1 (slightly acidic).
Did spring come early in San Rafael, CA in 2026?
Spring leaf-out near 94903 came on Jan 29 in 2026, about the same as the 1991–2020 average (Jan 29), according to the USA National Phenology Network Spring Index.
What kind of onions grow in San Rafael, CA?
Intermediate onions: the longest day near 94903 is 14 h 48 min, so day-neutral types bulb best; long-day varieties may not bulb fully.
Did the zone for 94903 change?
Yes. The 2012 USDA map put 94903 in zone 10a; the 2023 map puts it in zone 9b. The newer map uses 1991–2020 data and more weather stations.