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

Planting zone for 93531 — Keene, CA

ZIP code 93531 (Keene, Kern County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is April 28 and the first fall frost October 26.

Where ZIP 93531 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 frostApr 28
First frostOct 26
2012 zone8b

Was 8b on the 2012 map — half a zone warmer 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 Keene, 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 Keene, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 28median — 50% chance of a later frost
Safe for tender plantsMay 21only 10% chance of frost after
First fall frostOctober 26median — 10% chance by Oct 4
Growing season183 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 12 and returns around November 16.

From the NOAA station Tehachapi 4 Se, CA — 14 miles away, elevation 4,219 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 93531

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 17 – Mar 31
SpinachSow outdoors · Mar 17 – Apr 7
Broccoli, cabbageStart indoors · Feb 17 – Mar 3
Broccoli, cabbageTransplant · Apr 7 – Apr 21
Onion setsPlant outdoors · Mar 31 – Apr 14
PotatoesPlant outdoors · Apr 7 – Apr 21
LettuceSow outdoors · Mar 31 – Apr 14
Carrots, beetsSow outdoors · Apr 7 – Apr 21
TomatoesStart indoors · Mar 3 – Mar 17
TomatoesTransplant · May 5 – May 19
Peppers, eggplantStart indoors · Feb 17 – Mar 3
Peppers, eggplantTransplant · May 12 – May 26
BeansSow outdoors · May 5 – May 19
Sweet cornSow outdoors · May 5 – May 19
Cucumbers, squashSow outdoors · May 5 – May 19
Fall lettuce, spinachSow outdoors · Aug 31 – Sep 14
GarlicPlant cloves · Oct 12 – Nov 16
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 28) and first fall frost (Oct 26) 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 93531 came on Jan 20 — 14 days earlier than the 1991–2020 average (Feb 3).

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 Keene, CA

The soil mapped at the center of ZIP 93531 is Walong — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding
pH7.2neutral; 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: Walong sandy loam, 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 93531; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Keene, CA

Summer high86 °Faverage high, July
Winter low31 °Faverage low, February
Hot days28days a year at 90 °F or more
Freezing nights82nights a year at 32 °F or less
Growing degree days2,922base 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
Precipitation10.7 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 52 °F, low 32 °F 52°32° JanFebruary: average high 53 °F, low 31 °F 53°31° FebMarch: average high 57 °F, low 34 °F 57°34° MarApril: average high 61 °F, low 37 °F 61°37° AprMay: average high 69 °F, low 44 °F 69°44° MayJune: average high 79 °F, low 52 °F 79°52° JunJuly: average high 86 °F, low 58 °F 86°58° JulAugust: average high 86 °F, low 57 °F 86°57° AugSeptember: average high 81 °F, low 51 °F 81°51° SepOctober: average high 71 °F, low 43 °F 71°43° OctNovember: average high 59 °F, low 37 °F 59°37° NovDecember: average high 51 °F, low 31 °F 51°31° Dec

Precipitation by month inches

0″1″2″3″January: 2.12 in precipitation 2.1 JanFebruary: 1.73 in precipitation 1.7 FebMarch: 1.99 in precipitation 2.0 MarApril: 0.97 in precipitation 1.0 AprMay: 0.49 in precipitation 0.5 MayJune: 0.11 in precipitation 0.1 JunJuly: 0.07 in precipitation 0.1 JulAugust: 0.02 in precipitation 0.0 AugSeptember: 0.16 in precipitation 0.2 SepOctober: 0.42 in precipitation 0.4 OctNovember: 1.06 in precipitation 1.1 NovDecember: 1.56 in precipitation 1.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Tehachapi 4 Se, CA (14 mi away); precipitation: Walker Basin 0.9 E, CA (14 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

935818b
Tehachapi, CA · 9 mi
935618b
Tehachapi, CA · 11 mi
935188b
Caliente, CA · 13 mi
932209b
Edison, CA · 14 mi
932039b
Arvin, CA · 15 mi
932419b
Lamont, CA · 17 mi
933039b
Bakersfield, CA · 17 mi
933809b
Bakersfield, CA · 17 mi

California planting zones →

Questions about 93531

What planting zone is ZIP code 93531?

ZIP code 93531 (Keene, 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 Keene, CA?

The median last spring frost (32 °F) near 93531 is April 28; after May 21 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Tehachapi 4 Se station.

When is the first frost in Keene, CA?

The median first fall frost near 93531 is October 26, giving a median frost-free growing season of 183 days.

When should I plant tomatoes in 93531?

Start tomato seeds indoors around Mar 3 – Mar 17 and set transplants outside around May 5 – May 19, one to three weeks after the median last frost.

How much rain and snow does 93531 get?

About 10.7 inches of precipitation a year (NOAA 1991–2020 normals, Walker Basin 0.9 E station).

How hot do summers get in Keene, CA?

The average high peaks at 86 °F in July, with about 28 days a year at 90 °F or more.

What kind of soil does 93531 have?

The USDA soil survey maps Walong at the center of ZIP 93531: sandy loam, well drained, pH about 7.2 (neutral).

Did spring come early in Keene, CA in 2026?

Spring leaf-out near 93531 came on Jan 20 in 2026, 14 days earlier than the 1991–2020 average (Feb 3), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Keene, CA?

Intermediate onions: the longest day near 93531 is 14 h 32 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 93531 change?

Yes. The 2012 USDA map put 93531 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.