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

Planting zone for 92398 — Yermo, CA

ZIP code 92398 (Yermo, San Bernardino County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 19 and the first fall frost November 26.

Where ZIP 92398 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 19
First frostNov 26
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 Yermo, 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 Yermo, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 19median — 50% chance of a later frost
Safe for tender plantsMarch 11only 10% chance of frost after
First fall frostNovember 26median — 10% chance by Nov 10
Growing season279 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 28 and returns around December 9.

From the NOAA station Barstow Daggett Airport, CA — 10 miles away, elevation 1,916 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 92398

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 8 – Jan 22
SpinachSow outdoors · Jan 8 – Jan 29
Broccoli, cabbageStart indoors · Dec 11 – Dec 25
Broccoli, cabbageTransplant · Jan 29 – Feb 12
Onion setsPlant outdoors · Jan 22 – Feb 5
PotatoesPlant outdoors · Jan 29 – Feb 12
LettuceSow outdoors · Jan 22 – Feb 5
Carrots, beetsSow outdoors · Jan 29 – Feb 12
TomatoesStart indoors · Dec 25 – Jan 8
TomatoesTransplant · Feb 26 – Mar 12
Peppers, eggplantStart indoors · Dec 11 – Dec 25
Peppers, eggplantTransplant · Mar 5 – Mar 19
BeansSow outdoors · Feb 26 – Mar 12
Sweet cornSow outdoors · Feb 26 – Mar 12
Cucumbers, squashSow outdoors · Feb 26 – Mar 12
Fall lettuce, spinachSow outdoors · Oct 1 – Oct 15
GarlicPlant cloves · Nov 12 – Dec 17
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 19) and first fall frost (Nov 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 92398 came on Jan 28 — 4 days earlier than the 1991–2020 average (Feb 1).

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 Yermo, CA

The soil mapped at the center of ZIP 92398 is Typic Haplargids — cobbly fine sandy loam, well drained.

TextureCobbly fine sandy loamdrains and warms fast; dries out and needs more feeding
pH7.5slightly alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter0.2%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Typic Haplargids and Lithic Haplargids; thermic 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 92398; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Yermo, CA

Summer high105 °Faverage high, July
Winter low35 °Faverage low, December
Hot days145days a year at 90 °F or more
Freezing nights24nights a year at 32 °F or less
Growing degree days6,868base 50 °F — the season’s usable heat
Longest day14 h 31 mindaylight on June 21
Shortest day9 h 48 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation3.8 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 61 °F, low 36 °F 61°36° JanFebruary: average high 66 °F, low 40 °F 66°40° FebMarch: average high 73 °F, low 46 °F 73°46° MarApril: average high 80 °F, low 51 °F 80°51° AprMay: average high 89 °F, low 60 °F 89°60° MayJune: average high 99 °F, low 68 °F 99°68° JunJuly: average high 105 °F, low 74 °F 105°74° JulAugust: average high 104 °F, low 73 °F 104°73° AugSeptember: average high 96 °F, low 66 °F 96°66° SepOctober: average high 83 °F, low 54 °F 83°54° OctNovember: average high 70 °F, low 43 °F 70°43° NovDecember: average high 60 °F, low 35 °F 60°35° Dec

Precipitation by month inches

0″1″January: 0.57 in precipitation 0.6 JanFebruary: 0.70 in precipitation 0.7 FebMarch: 0.43 in precipitation 0.4 MarApril: 0.22 in precipitation 0.2 AprMay: 0.05 in precipitation 0.1 MayJune: 0.03 in precipitation 0.0 JunJuly: 0.28 in precipitation 0.3 JulAugust: 0.20 in precipitation 0.2 AugSeptember: 0.17 in precipitation 0.2 SepOctober: 0.24 in precipitation 0.2 OctNovember: 0.32 in precipitation 0.3 NovDecember: 0.56 in precipitation, 0.2 in snowfall 0.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Barstow Daggett Airport, CA (10 mi away); precipitation: Barstow Daggett Airport, CA (10 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.

923279a
Daggett, CA · 8 mi
923119a
Barstow, CA · 9 mi
923129a
Barstow, CA · 11 mi
923659a
Newberry Springs, CA · 18 mi
923479a
Hinkley, CA · 23 mi
923109a
Fort Irwin, CA · 25 mi
923428b
Helendale, CA · 31 mi
923078b
Apple Valley, CA · 33 mi

California planting zones →

Questions about 92398

What planting zone is ZIP code 92398?

ZIP code 92398 (Yermo, 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 Yermo, CA?

The median last spring frost (32 °F) near 92398 is February 19; after March 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Barstow Daggett Airport station.

When is the first frost in Yermo, CA?

The median first fall frost near 92398 is November 26, giving a median frost-free growing season of 279 days.

When should I plant tomatoes in 92398?

Start tomato seeds indoors around Dec 25 – Jan 8 and set transplants outside around Feb 26 – Mar 12, one to three weeks after the median last frost.

How much rain and snow does 92398 get?

About 3.8 inches of precipitation a year (NOAA 1991–2020 normals, Barstow Daggett Airport station).

How hot do summers get in Yermo, CA?

The average high peaks at 105 °F in July, with about 145 days a year at 90 °F or more.

What kind of soil does 92398 have?

The USDA soil survey maps Typic Haplargids at the center of ZIP 92398: cobbly fine sandy loam, well drained, pH about 7.5 (slightly alkaline).

Did spring come early in Yermo, CA in 2026?

Spring leaf-out near 92398 came on Jan 28 in 2026, 4 days earlier than the 1991–2020 average (Feb 1), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Yermo, CA?

Intermediate onions: the longest day near 92398 is 14 h 31 min, so day-neutral types bulb best; long-day varieties may not bulb fully.