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

Planting zone for 92309 — Baker, CA

ZIP code 92309 (Baker, San Bernardino County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 14 and the first fall frost November 27.

Where ZIP 92309 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 frostFeb 14
First frostNov 27
2012 zone9a

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 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Baker, 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 Baker, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 14median — 50% chance of a later frost
Safe for tender plantsMarch 4only 10% chance of frost after
First fall frostNovember 27median — 10% chance by Nov 12
Growing season287 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 30 and returns around December 8.

From the NOAA station Baker, CA — 6 miles away, elevation 961 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 92309

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 3 – Jan 17
SpinachSow outdoors · Jan 3 – Jan 24
Broccoli, cabbageStart indoors · Dec 6 – Dec 20
Broccoli, cabbageTransplant · Jan 24 – Feb 7
Onion setsPlant outdoors · Jan 17 – Jan 31
PotatoesPlant outdoors · Jan 24 – Feb 7
LettuceSow outdoors · Jan 17 – Jan 31
Carrots, beetsSow outdoors · Jan 24 – Feb 7
TomatoesStart indoors · Dec 20 – Jan 3
TomatoesTransplant · Feb 21 – Mar 7
Peppers, eggplantStart indoors · Dec 6 – Dec 20
Peppers, eggplantTransplant · Feb 28 – Mar 14
BeansSow outdoors · Feb 21 – Mar 7
Sweet cornSow outdoors · Feb 21 – Mar 7
Cucumbers, squashSow outdoors · Feb 21 – Mar 7
Fall lettuce, spinachSow outdoors · Oct 2 – Oct 16
GarlicPlant cloves · Nov 13 – Dec 18
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 14) and first fall frost (Nov 27) 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 92309 came on Jan 28 — 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 Baker, CA

The soil mapped at the center of ZIP 92309 is Lithic Torriorthents — very gravelly fine sandy loam, somewhat excessively drained.

TextureVery gravelly fine sandy loamdrains and warms fast; dries out and needs more feeding
pH7.8slightly alkaline; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter0.3%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Lithic Torriorthents, Typic Haplocalcids, and Rock outcrop; hyperthermic hills and mountains.

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 92309; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Baker, CA

Summer high110 °Faverage high, July
Winter low33 °Faverage low, December
Hot days163days a year at 90 °F or more
Freezing nights33nights a year at 32 °F or less
Growing degree days7,680base 50 °F — the season’s usable heat
Longest day14 h 32 mindaylight on June 21
Shortest day9 h 47 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation4.3 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°110°120°32 °FJanuary: average high 63 °F, low 35 °F 63°35° JanFebruary: average high 69 °F, low 40 °F 69°40° FebMarch: average high 77 °F, low 46 °F 77°46° MarApril: average high 84 °F, low 53 °F 84°53° AprMay: average high 93 °F, low 62 °F 93°62° MayJune: average high 104 °F, low 72 °F 104°72° JunJuly: average high 110 °F, low 78 °F 110°78° JulAugust: average high 108 °F, low 76 °F 108°76° AugSeptember: average high 101 °F, low 68 °F 101°68° SepOctober: average high 87 °F, low 54 °F 87°54° OctNovember: average high 72 °F, low 42 °F 72°42° NovDecember: average high 62 °F, low 33 °F 62°33° Dec

Precipitation by month inches

0″1″January: 0.52 in precipitation 0.5 JanFebruary: 0.90 in precipitation 0.9 FebMarch: 0.43 in precipitation 0.4 MarApril: 0.13 in precipitation 0.1 AprMay: 0.25 in precipitation 0.3 MayJune: 0.02 in precipitation 0.0 JunJuly: 0.32 in precipitation 0.3 JulAugust: 0.27 in precipitation 0.3 AugSeptember: 0.36 in precipitation 0.4 SepOctober: 0.20 in precipitation 0.2 OctNovember: 0.35 in precipitation 0.3 NovDecember: 0.58 in precipitation 0.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Baker, CA (6 mi away); precipitation: Baker, CA (6 mi away). 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.

923389a
Ludlow, CA · 32 mi
923659a
Newberry Springs, CA · 33 mi
923109a
Fort Irwin, CA · 35 mi
923238b
Cima, CA · 37 mi
923668b
Mountain Pass, CA · 38 mi
923899a
Tecopa, CA · 40 mi
923648b
Nipton, CA · 41 mi
923989a
Yermo, CA · 43 mi

California planting zones →

Questions about 92309

What planting zone is ZIP code 92309?

ZIP code 92309 (Baker, 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 Baker, CA?

The median last spring frost (32 °F) near 92309 is February 14; after March 4 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Baker station.

When is the first frost in Baker, CA?

The median first fall frost near 92309 is November 27, giving a median frost-free growing season of 287 days.

When should I plant tomatoes in 92309?

Start tomato seeds indoors around Dec 20 – Jan 3 and set transplants outside around Feb 21 – Mar 7, one to three weeks after the median last frost.

How much rain and snow does 92309 get?

About 4.3 inches of precipitation a year (NOAA 1991–2020 normals, Baker station).

How hot do summers get in Baker, CA?

The average high peaks at 110 °F in July, with about 163 days a year at 90 °F or more.

What kind of soil does 92309 have?

The USDA soil survey maps Lithic Torriorthents at the center of ZIP 92309: very gravelly fine sandy loam, somewhat excessively drained, pH about 7.8 (slightly alkaline).

Did spring come early in Baker, CA in 2026?

Spring leaf-out near 92309 came on Jan 28 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 Baker, CA?

Intermediate onions: the longest day near 92309 is 14 h 32 min, so day-neutral types bulb best; long-day varieties may not bulb fully.