Planting zone for 94940 — Marshall, CA
ZIP code 94940 (Marshall, Marin County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F.
Where ZIP 94940 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 Marshall, 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 Bodega 6 Wsw, CA — 13 miles away, elevation 62 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 94940 came on Jan 27 — 3 days earlier than the 1991–2020 average (Jan 30).
Jan 302026
Jan 27
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 Marshall, CA
The soil mapped at the center of ZIP 94940 is Saurin — clay loam, well drained.
Map unit: Saurin-Bonnydoon complex, 2 to 15 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 94940; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.
Climate in Marshall, CA
Average high and low, by month
Precipitation by month inches
NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Bodega 6 Wsw, CA (13 mi away); precipitation: Petaluma 10.1 W, CA (5 mi away). Daylight is calculated from latitude.
Nearby ZIP codes
4 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.
Questions about 94940
What planting zone is ZIP code 94940?
ZIP code 94940 (Marshall, 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 94940 get?
About 32.6 inches of precipitation a year (NOAA 1991–2020 normals, Petaluma 10.1 W station).
How hot do summers get in Marshall, CA?
The average high peaks at 66 °F in September, with about 0 days a year at 90 °F or more.
What kind of soil does 94940 have?
The USDA soil survey maps Saurin at the center of ZIP 94940: clay loam, well drained, pH about 6.1 (slightly acidic).
Did spring come early in Marshall, CA in 2026?
Spring leaf-out near 94940 came on Jan 27 in 2026, 3 days earlier than the 1991–2020 average (Jan 30), according to the USA National Phenology Network Spring Index.
What kind of onions grow in Marshall, CA?
Intermediate onions: the longest day near 94940 is 14 h 49 min, so day-neutral types bulb best; long-day varieties may not bulb fully.
Did the zone for 94940 change?
Yes. The 2012 USDA map put 94940 in zone 10a; the 2023 map puts it in zone 9b. The newer map uses 1991–2020 data and more weather stations.