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

Planting zone for Alpine, CA

Alpine, CA is in USDA zone 9b across its 2 ZIP codes. The median last spring frost is February 12 and the first fall frost December 24.

Alpine on the zone map

Outlined: its 1 ZIP code areas · 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
ZIP codes2
Last frostFeb 12
First frostDec 24
Growing season317 days

9b 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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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 Alpine, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 12median — 50% chance of a later frost
Safe for tender plantsMarch 20only 10% chance of frost after
First fall frostDecember 24median — 10% chance by Dec 2
Growing season317 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 22 and returns around January 4.

From the NOAA station Alpine, CA, elevation 1,696 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 Alpine

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 1 – Jan 15
SpinachSow outdoors · Jan 1 – Jan 22
Broccoli, cabbageStart indoors · Dec 4 – Dec 18
Broccoli, cabbageTransplant · Jan 22 – Feb 5
Onion setsPlant outdoors · Jan 15 – Jan 29
PotatoesPlant outdoors · Jan 22 – Feb 5
LettuceSow outdoors · Jan 15 – Jan 29
Carrots, beetsSow outdoors · Jan 22 – Feb 5
TomatoesStart indoors · Dec 18 – Jan 1
TomatoesTransplant · Feb 19 – Mar 5
Peppers, eggplantStart indoors · Dec 4 – Dec 18
Peppers, eggplantTransplant · Feb 26 – Mar 12
BeansSow outdoors · Feb 19 – Mar 5
Sweet cornSow outdoors · Feb 19 – Mar 5
Cucumbers, squashSow outdoors · Feb 19 – Mar 5
Fall lettuce, spinachSow outdoors · Oct 29 – Nov 12
GarlicPlant cloves · Dec 10 – Jan 14
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 12) and first fall frost (Dec 24) 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 91903 came on Jan 17 — 8 days earlier than the 1991–2020 average (Jan 25).

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 Alpine, CA

The soil mapped at the center of ZIP 91903 is Visalia — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding
pH6.3slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupAwater soaks in fast
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Visalia sandy loam, 2 to 5 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 91903; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Alpine, CA

Summer high89 °Faverage high, August
Winter low42 °Faverage low, February
Hot days55days a year at 90 °F or more
Freezing nights3nights a year at 32 °F or less
Growing degree days4,757base 50 °F — the season’s usable heat
Longest day14 h 19 mindaylight on June 21
Shortest day9 h 59 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation16.1 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°32 °FJanuary: average high 64 °F, low 43 °F 64°43° JanFebruary: average high 64 °F, low 42 °F 64°42° FebMarch: average high 67 °F, low 44 °F 67°44° MarApril: average high 71 °F, low 47 °F 71°47° AprMay: average high 74 °F, low 51 °F 74°51° MayJune: average high 81 °F, low 54 °F 81°54° JunJuly: average high 87 °F, low 60 °F 87°60° JulAugust: average high 89 °F, low 62 °F 89°62° AugSeptember: average high 86 °F, low 60 °F 86°60° SepOctober: average high 78 °F, low 54 °F 78°54° OctNovember: average high 71 °F, low 48 °F 71°48° NovDecember: average high 63 °F, low 42 °F 63°42° Dec

Precipitation by month inches

0″1″2″3″4″January: 3.21 in precipitation 3.2 JanFebruary: 3.65 in precipitation 3.6 FebMarch: 2.73 in precipitation 2.7 MarApril: 1.18 in precipitation 1.2 AprMay: 0.57 in precipitation 0.6 MayJune: 0.13 in precipitation 0.1 JunJuly: 0.10 in precipitation 0.1 JulAugust: 0.12 in precipitation 0.1 AugSeptember: 0.25 in precipitation 0.3 SepOctober: 0.59 in precipitation 0.6 OctNovember: 1.48 in precipitation 1.5 NovDecember: 2.04 in precipitation 2.0 Dec

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

ZIP codes in Alpine

919019b
25 to 30 °F
919039b
25 to 30 °F

California planting zones →

Questions about Alpine

What planting zone is Alpine, CA?

Alpine, CA is in USDA hardiness zone 9b on the 2023 map (9b: 25 to 30 °F).

When is the last frost in Alpine, CA?

The median last spring frost is February 12 and the median first fall frost is December 24 (NOAA 1991–2020 normals, Alpine station).

When can I plant a garden in Alpine, CA?

Cool-season crops like peas and spinach go in around Jan 1 – Jan 22; tomatoes, peppers, beans and squash after about Feb 19, once frost risk has passed.

What kind of onions grow in Alpine, CA?

Intermediate onions: the longest day is 14 h 19 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

How much rain and snow does Alpine, CA get?

About 16.1 inches of precipitation a year (NOAA 1991–2020 normals).