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

Planting zone for 94957 — Ross, CA

ZIP code 94957 (Ross, Marin County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F.

Where ZIP 94957 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.

Zone9b25 to 30 °F
Coldest night−3.9 to −1.1 °C
Last frostrare
First frostrare
2012 zone9b

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 9b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Ross, 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 Kentfield, CA — within 1 mile, elevation 144 ft) the median growing season is 334 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 94957 came on Jan 27 — about the same time as the 1991–2020 average (Jan 29).

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 Ross, CA

The soil mapped at the center of ZIP 94957 is Tocaloma — loam, well drained.

TextureLoama good balance for most vegetables
pH6.1slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Tocaloma-McMullin-Urban land complex, 30 to 50 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 94957; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Ross, CA

Summer high83 °Faverage high, July
Winter low42 °Faverage low, January
Hot days27days a year at 90 °F or more
Freezing nights5nights a year at 32 °F or less
Growing degree days3,578base 50 °F — the season’s usable heat
Longest day14 h 48 mindaylight on June 21
Shortest day9 h 32 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation44.4 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°32 °FJanuary: average high 57 °F, low 42 °F 57°42° JanFebruary: average high 61 °F, low 43 °F 61°43° FebMarch: average high 65 °F, low 44 °F 65°44° MarApril: average high 69 °F, low 46 °F 69°46° AprMay: average high 74 °F, low 50 °F 74°50° MayJune: average high 80 °F, low 52 °F 80°52° JunJuly: average high 83 °F, low 53 °F 83°53° JulAugust: average high 83 °F, low 54 °F 83°54° AugSeptember: average high 82 °F, low 53 °F 82°53° SepOctober: average high 76 °F, low 50 °F 76°50° OctNovember: average high 64 °F, low 45 °F 64°45° NovDecember: average high 56 °F, low 42 °F 56°42° Dec

Precipitation by month inches

0″2″4″6″8″10″January: 8.77 in precipitation 8.8 JanFebruary: 8.72 in precipitation 8.7 FebMarch: 6.00 in precipitation 6.0 MarApril: 2.61 in precipitation 2.6 AprMay: 1.40 in precipitation 1.4 MayJune: 0.36 in precipitation 0.4 JunJuly: 0.00 in precipitation 0.0 JulAugust: 0.05 in precipitation 0.1 AugSeptember: 0.09 in precipitation 0.1 SepOctober: 1.98 in precipitation 2.0 OctNovember: 4.63 in precipitation 4.6 NovDecember: 9.78 in precipitation 9.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Kentfield, CA (within 1 mile); precipitation: Kentfield, CA (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

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

949799b
San Anselmo, CA · <1 mi
949149b
Kentfield, CA · <1 mi
949049b
Greenbrae, CA · 1 mi
9491210a
San Rafael, CA · 2 mi
949139b
San Rafael, CA · 2 mi
949789b
Fairfax, CA · 2 mi
9493910a
Larkspur, CA · 2 mi
9497710a
Larkspur, CA · 2 mi

California planting zones →

Questions about 94957

What planting zone is ZIP code 94957?

ZIP code 94957 (Ross, 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 94957 get?

About 44.4 inches of precipitation a year (NOAA 1991–2020 normals, Kentfield station).

How hot do summers get in Ross, CA?

The average high peaks at 83 °F in July, with about 27 days a year at 90 °F or more.

What kind of soil does 94957 have?

The USDA soil survey maps Tocaloma at the center of ZIP 94957: loam, well drained, pH about 6.1 (slightly acidic).

Did spring come early in Ross, CA in 2026?

Spring leaf-out near 94957 came on Jan 27 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 Ross, CA?

Intermediate onions: the longest day near 94957 is 14 h 48 min, so day-neutral types bulb best; long-day varieties may not bulb fully.