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

Planting zone for 93592 — Trona, CA

ZIP code 93592 (Trona, San Bernardino County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 15 and the first fall frost November 28.

Where ZIP 93592 is

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 15
First frostNov 28
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

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Loading the forecast for Trona, 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 Trona, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 15median — 50% chance of a later frost
Safe for tender plantsMarch 4only 10% chance of frost after
First fall frostNovember 28median — 10% chance by Nov 11
Growing season285 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 23 and returns around December 10.

From the NOAA station Trona, CA — within 1 mile, 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 93592

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 4 – Jan 18
SpinachSow outdoors · Jan 4 – Jan 25
Broccoli, cabbageStart indoors · Dec 7 – Dec 21
Broccoli, cabbageTransplant · Jan 25 – Feb 8
Onion setsPlant outdoors · Jan 18 – Feb 1
PotatoesPlant outdoors · Jan 25 – Feb 8
LettuceSow outdoors · Jan 18 – Feb 1
Carrots, beetsSow outdoors · Jan 25 – Feb 8
TomatoesStart indoors · Dec 21 – Jan 4
TomatoesTransplant · Feb 22 – Mar 8
Peppers, eggplantStart indoors · Dec 7 – Dec 21
Peppers, eggplantTransplant · Mar 1 – Mar 15
BeansSow outdoors · Feb 22 – Mar 8
Sweet cornSow outdoors · Feb 22 – Mar 8
Cucumbers, squashSow outdoors · Feb 22 – Mar 8
Fall lettuce, spinachSow outdoors · Oct 3 – Oct 17
GarlicPlant cloves · Nov 14 – Dec 19
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 15) and first fall frost (Nov 28) 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 93592 came on Jan 28 — 3 days earlier than the 1991–2020 average (Jan 31).

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 Trona, CA

The soil mapped at the center of ZIP 93592 is Torriorthents — extremely gravelly sand, somewhat excessively drained.

TextureExtremely gravelly sanddrains and warms fast; dries out and needs more feeding
pH8.0alkaline; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter0.2%low — add compost
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Torriorthents, Torripsamments, and Haplargids; hyperthermic fan piedmonts.

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 93592; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Trona, CA

Summer high107 °Faverage high, July
Winter low34 °Faverage low, December
Hot days137days a year at 90 °F or more
Freezing nights26nights a year at 32 °F or less
Growing degree days7,073base 50 °F — the season’s usable heat
Longest day14 h 35 mindaylight on June 21
Shortest day9 h 44 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation3.6 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 60 °F, low 35 °F 60°35° JanFebruary: average high 66 °F, low 39 °F 66°39° FebMarch: average high 73 °F, low 45 °F 73°45° MarApril: average high 81 °F, low 51 °F 81°51° AprMay: average high 90 °F, low 59 °F 90°59° MayJune: average high 100 °F, low 68 °F 100°68° JunJuly: average high 107 °F, low 74 °F 107°74° JulAugust: average high 106 °F, low 74 °F 106°74° AugSeptember: average high 99 °F, low 67 °F 99°67° SepOctober: average high 86 °F, low 55 °F 86°55° OctNovember: average high 71 °F, low 42 °F 71°42° NovDecember: average high 60 °F, low 34 °F 60°34° Dec

Precipitation by month inches

0″1″January: 0.77 in precipitation 0.8 JanFebruary: 0.91 in precipitation 0.9 FebMarch: 0.48 in precipitation 0.5 MarApril: 0.11 in precipitation 0.1 AprMay: 0.07 in precipitation 0.1 MayJune: 0.02 in precipitation 0.0 JunJuly: 0.09 in precipitation 0.1 JulAugust: 0.06 in precipitation 0.1 AugSeptember: 0.09 in precipitation 0.1 SepOctober: 0.20 in precipitation 0.2 OctNovember: 0.24 in precipitation 0.2 NovDecember: 0.58 in precipitation 0.6 Dec

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

Nearby ZIP codes

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

935629a
Trona, CA · 6 mi
935568b
Ridgecrest, CA · 19 mi
935558b
Ridgecrest, CA · 21 mi
935289a
Johannesburg, CA · 31 mi
935589a
Red Mountain, CA · 32 mi
935428b
Little Lake, CA · 32 mi
935549a
Randsburg, CA · 35 mi
935228b
Darwin, CA · 40 mi

All 2 ZIP codes in Trona → · California planting zones →

Questions about 93592

What planting zone is ZIP code 93592?

ZIP code 93592 (Trona, 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 Trona, CA?

The median last spring frost (32 °F) near 93592 is February 15; after March 4 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Trona station.

When is the first frost in Trona, CA?

The median first fall frost near 93592 is November 28, giving a median frost-free growing season of 285 days.

When should I plant tomatoes in 93592?

Start tomato seeds indoors around Dec 21 – Jan 4 and set transplants outside around Feb 22 – Mar 8, one to three weeks after the median last frost.

How much rain and snow does 93592 get?

About 3.6 inches of precipitation a year (NOAA 1991–2020 normals, Trona station).

How hot do summers get in Trona, CA?

The average high peaks at 107 °F in July, with about 137 days a year at 90 °F or more.

What kind of soil does 93592 have?

The USDA soil survey maps Torriorthents at the center of ZIP 93592: extremely gravelly sand, somewhat excessively drained, pH about 8.0 (alkaline).

Did spring come early in Trona, CA in 2026?

Spring leaf-out near 93592 came on Jan 28 in 2026, 3 days earlier than the 1991–2020 average (Jan 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Trona, CA?

Intermediate onions: the longest day near 93592 is 14 h 35 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 93592 change?

Yes. The 2012 USDA map put 93592 in zone 9b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.