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

Planting zone for 95403 — Santa Rosa, CA

ZIP code 95403 (Santa Rosa, Sonoma County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is March 2 and the first fall frost November 20.

Where ZIP 95403 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.

Zone9a20 to 25 °F
Coldest night−6.7 to −3.9 °C
Last frostMar 2
First frostNov 20
2012 zone9b

Was 9b 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 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Santa Rosa, 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 in Santa Rosa, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 2median — 50% chance of a later frost
Safe for tender plantsApril 2only 10% chance of frost after
First fall frostNovember 20median — 10% chance by Nov 1
Growing season262 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 23 and returns around December 5.

From the NOAA station Santa Rosa Sonoma Co. Airport, CA — 3 miles away, elevation 115 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 95403

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 19 – Feb 2
SpinachSow outdoors · Jan 19 – Feb 9
Broccoli, cabbageStart indoors · Dec 22 – Jan 5
Broccoli, cabbageTransplant · Feb 9 – Feb 23
Onion setsPlant outdoors · Feb 2 – Feb 16
PotatoesPlant outdoors · Feb 9 – Feb 23
LettuceSow outdoors · Feb 2 – Feb 16
Carrots, beetsSow outdoors · Feb 9 – Feb 23
TomatoesStart indoors · Jan 5 – Jan 19
TomatoesTransplant · Mar 9 – Mar 23
Peppers, eggplantStart indoors · Dec 22 – Jan 5
Peppers, eggplantTransplant · Mar 16 – Mar 30
BeansSow outdoors · Mar 9 – Mar 23
Sweet cornSow outdoors · Mar 9 – Mar 23
Cucumbers, squashSow outdoors · Mar 9 – Mar 23
Fall lettuce, spinachSow outdoors · Sep 25 – Oct 9
GarlicPlant cloves · Nov 6 – Dec 11
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 2) and first fall frost (Nov 20) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 95403 came on Jan 29 — about the same time as the 1991–2020 average (Jan 30).

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 Santa Rosa, CA

The soil mapped at the center of ZIP 95403 is Zamora — silty clay loam, well drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.2slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupCwater soaks in slowly
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Zamora silty clay loam, moist, 0 to 2 percent slopes, MLRA 14.

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 95403; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Santa Rosa, CA

Summer high84 °Faverage high, July
Winter low37 °Faverage low, December
Hot days34days a year at 90 °F or more
Freezing nights31nights a year at 32 °F or less
Growing degree days3,302base 50 °F — the season’s usable heat
Longest day14 h 51 mindaylight on June 21
Shortest day9 h 28 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation33.5 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 38 °F 58°38° JanFebruary: average high 62 °F, low 39 °F 62°39° FebMarch: average high 65 °F, low 41 °F 65°41° MarApril: average high 69 °F, low 43 °F 69°43° AprMay: average high 75 °F, low 47 °F 75°47° MayJune: average high 82 °F, low 50 °F 82°50° JunJuly: average high 84 °F, low 52 °F 84°52° JulAugust: average high 84 °F, low 52 °F 84°52° AugSeptember: average high 83 °F, low 50 °F 83°50° SepOctober: average high 77 °F, low 46 °F 77°46° OctNovember: average high 65 °F, low 40 °F 65°40° NovDecember: average high 58 °F, low 37 °F 58°37° Dec

Precipitation by month inches

0″2″4″6″8″January: 5.82 in precipitation 5.8 JanFebruary: 7.01 in precipitation 7.0 FebMarch: 4.40 in precipitation 4.4 MarApril: 2.17 in precipitation 2.2 AprMay: 1.31 in precipitation 1.3 MayJune: 0.35 in precipitation 0.3 JunJuly: 0.02 in precipitation 0.0 JulAugust: 0.07 in precipitation 0.1 AugSeptember: 0.14 in precipitation 0.1 SepOctober: 1.79 in precipitation 1.8 OctNovember: 3.54 in precipitation 3.5 NovDecember: 6.92 in precipitation 6.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Santa Rosa Sonoma Co. Airport, CA (3 mi away); precipitation: Santa Rosa 2.3 Nw, CA (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

954399a
Fulton, CA · 1 mi
954929a
Windsor, CA · 4 mi
954049b
Santa Rosa, CA · 4 mi
954019a
Santa Rosa, CA · 4 mi
954029b
Santa Rosa, CA · 5 mi
954069a
Santa Rosa, CA · 5 mi
954059a
Santa Rosa, CA · 6 mi
954079a
Santa Rosa, CA · 8 mi

All 8 ZIP codes in Santa Rosa → · California planting zones →

Questions about 95403

What planting zone is ZIP code 95403?

ZIP code 95403 (Santa Rosa, CA) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in Santa Rosa, CA?

The median last spring frost (32 °F) near 95403 is March 2; after April 2 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Santa Rosa Sonoma Co. Airport station.

When is the first frost in Santa Rosa, CA?

The median first fall frost near 95403 is November 20, giving a median frost-free growing season of 262 days.

When should I plant tomatoes in 95403?

Start tomato seeds indoors around Jan 5 – Jan 19 and set transplants outside around Mar 9 – Mar 23, one to three weeks after the median last frost.

How much rain and snow does 95403 get?

About 33.5 inches of precipitation a year (NOAA 1991–2020 normals, Santa Rosa 2.3 Nw station).

How hot do summers get in Santa Rosa, CA?

The average high peaks at 84 °F in July, with about 34 days a year at 90 °F or more.

What kind of soil does 95403 have?

The USDA soil survey maps Zamora at the center of ZIP 95403: silty clay loam, well drained, pH about 6.2 (slightly acidic).

Did spring come early in Santa Rosa, CA in 2026?

Spring leaf-out near 95403 came on Jan 29 in 2026, about the same as the 1991–2020 average (Jan 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Santa Rosa, CA?

Intermediate onions: the longest day near 95403 is 14 h 51 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 95403 change?

Yes. The 2012 USDA map put 95403 in zone 9b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.