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

Planting zone for 94920 — Belvedere Tiburon, CA

ZIP code 94920 (Belvedere Tiburon, Marin County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.

Where ZIP 94920 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 Belvedere Tiburon, 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 Richmond, CA — 5 miles away, elevation 20 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 94920 came on Jan 24 — 3 days earlier than 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 Belvedere Tiburon, CA

The soil mapped at the center of ZIP 94920 is Henneke — stony clay loam, somewhat excessively drained.

TextureStony clay loamholds water and nutrients; slow to drain and warm up
pH7.0neutral; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter4.5%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Henneke stony clay loam, 15 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 94920; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Belvedere Tiburon, CA

Summer high75 °Faverage high, September
Winter low44 °Faverage low, January
Hot days5days a year at 90 °F or more
Freezing nights0nights a year at 32 °F or less
Growing degree days3,322base 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
Precipitation24.4 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°32 °FJanuary: average high 58 °F, low 44 °F 58°44° JanFebruary: average high 61 °F, low 46 °F 61°46° FebMarch: average high 64 °F, low 47 °F 64°47° MarApril: average high 67 °F, low 49 °F 67°49° AprMay: average high 69 °F, low 52 °F 69°52° MayJune: average high 72 °F, low 54 °F 72°54° JunJuly: average high 71 °F, low 55 °F 71°55° JulAugust: average high 72 °F, low 56 °F 72°56° AugSeptember: average high 75 °F, low 56 °F 75°56° SepOctober: average high 73 °F, low 54 °F 73°54° OctNovember: average high 65 °F, low 49 °F 65°49° NovDecember: average high 58 °F, low 44 °F 58°44° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 4.83 in precipitation 4.8 JanFebruary: 4.76 in precipitation 4.8 FebMarch: 3.17 in precipitation 3.2 MarApril: 1.57 in precipitation 1.6 AprMay: 0.72 in precipitation 0.7 MayJune: 0.27 in precipitation 0.3 JunJuly: 0.00 in precipitation 0.0 JulAugust: 0.07 in precipitation 0.1 AugSeptember: 0.03 in precipitation 0.0 SepOctober: 1.42 in precipitation 1.4 OctNovember: 2.67 in precipitation 2.7 NovDecember: 4.90 in precipitation 4.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Richmond, CA (5 mi away); precipitation: Richmond, CA (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 10a.

9496610a
Sausalito, CA · 2 mi
9497410a
San Quentin, CA · 4 mi
9492510a
Corte Madera, CA · 4 mi
9496410a
San Quentin, CA · 4 mi
9497610a
Corte Madera, CA · 4 mi
9494210a
Mill Valley, CA · 5 mi
9496510a
Sausalito, CA · 5 mi
9497710a
Larkspur, CA · 5 mi

California planting zones →

Questions about 94920

What planting zone is ZIP code 94920?

ZIP code 94920 (Belvedere Tiburon, 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 94920 get?

About 24.4 inches of precipitation a year (NOAA 1991–2020 normals, Richmond station).

How hot do summers get in Belvedere Tiburon, CA?

The average high peaks at 75 °F in September, with about 5 days a year at 90 °F or more.

What kind of soil does 94920 have?

The USDA soil survey maps Henneke at the center of ZIP 94920: stony clay loam, somewhat excessively drained, pH about 7.0 (neutral).

Did spring come early in Belvedere Tiburon, CA in 2026?

Spring leaf-out near 94920 came on Jan 24 in 2026, 3 days earlier than the 1991–2020 average (Jan 27), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Belvedere Tiburon, CA?

Intermediate onions: the longest day near 94920 is 14 h 48 min, so day-neutral types bulb best; long-day varieties may not bulb fully.