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

Planting zone for 91934 — Jacumba, CA

ZIP code 91934 (Jacumba, San Diego County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F. The median last spring frost is April 29 and the first fall frost November 1.

Where ZIP 91934 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.

Zone9b25 to 30 °F
Coldest night−3.9 to −1.1 °C
Last frostApr 29
First frostNov 1
2012 zone8b

Was 8b on the 2012 map — a full zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 9b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Jacumba, 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 Jacumba, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 29median — 50% chance of a later frost
Safe for tender plantsJune 1only 10% chance of frost after
First fall frostNovember 1median — 10% chance by Oct 5
Growing season184 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 31 and returns around November 27.

From the NOAA station Campo Asos, CA — 19 miles away, elevation 2,641 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 91934

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 18 – Apr 1
SpinachSow outdoors · Mar 18 – Apr 8
Broccoli, cabbageStart indoors · Feb 18 – Mar 4
Broccoli, cabbageTransplant · Apr 8 – Apr 22
Onion setsPlant outdoors · Apr 1 – Apr 15
PotatoesPlant outdoors · Apr 8 – Apr 22
LettuceSow outdoors · Apr 1 – Apr 15
Carrots, beetsSow outdoors · Apr 8 – Apr 22
TomatoesStart indoors · Mar 4 – Mar 18
TomatoesTransplant · May 6 – May 20
Peppers, eggplantStart indoors · Feb 18 – Mar 4
Peppers, eggplantTransplant · May 13 – May 27
BeansSow outdoors · May 6 – May 20
Sweet cornSow outdoors · May 6 – May 20
Cucumbers, squashSow outdoors · May 6 – May 20
Fall lettuce, spinachSow outdoors · Sep 6 – Sep 20
GarlicPlant cloves · Oct 18 – Nov 22
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 29) and first fall frost (Nov 1) 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 91934 came on Jan 24 — 7 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 Jacumba, CA

The soil mapped at the center of ZIP 91934 is Typic Haplocambids — gravelly loamy coarse sand, well drained.

TextureGravelly loamy coarse sanddrains and warms fast; dries out and needs more feeding
pH8.0alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Typic Haplocambids-Lithic Haplocalcids complex, cool, 5 to 50 percent slopes, eroded.

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 91934; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Jacumba, CA

Summer high93 °Faverage high, August
Winter low34 °Faverage low, December
Hot days76days a year at 90 °F or more
Freezing nights68nights a year at 32 °F or less
Growing degree days3,575base 50 °F — the season’s usable heat
Longest day14 h 18 mindaylight on June 21
Shortest day10 h 00 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation3.5 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 62 °F, low 35 °F 62°35° JanFebruary: average high 61 °F, low 35 °F 61°35° FebMarch: average high 65 °F, low 35 °F 65°35° MarApril: average high 69 °F, low 38 °F 69°38° AprMay: average high 76 °F, low 42 °F 76°42° MayJune: average high 85 °F, low 46 °F 85°46° JunJuly: average high 91 °F, low 54 °F 91°54° JulAugust: average high 93 °F, low 55 °F 93°55° AugSeptember: average high 88 °F, low 51 °F 88°51° SepOctober: average high 78 °F, low 43 °F 78°43° OctNovember: average high 69 °F, low 38 °F 69°38° NovDecember: average high 61 °F, low 34 °F 61°34° Dec

Precipitation by month inches

0″1″January: 0.65 in precipitation 0.7 JanFebruary: 0.50 in precipitation 0.5 FebMarch: 0.22 in precipitation 0.2 MarApril: 0.02 in precipitation 0.0 AprMay: 0.02 in precipitation 0.0 MayJune: 0.02 in precipitation 0.0 JunJuly: 0.32 in precipitation 0.3 JulAugust: 0.50 in precipitation 0.5 AugSeptember: 0.17 in precipitation 0.2 SepOctober: 0.29 in precipitation 0.3 OctNovember: 0.25 in precipitation 0.3 NovDecember: 0.52 in precipitation 0.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Campo Asos, CA (19 mi away); precipitation: Ocotillo 2, CA (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

919059a
Boulevard, CA · 9 mi
9225910a
Ocotillo, CA · 13 mi
919069a
Campo, CA · 19 mi
919488a
Mount Laguna, CA · 24 mi
919628b
Pine Valley, CA · 25 mi
919639a
Potrero, CA · 26 mi
920369b
Julian, CA · 27 mi
919318b
Guatay, CA · 28 mi

California planting zones →

Questions about 91934

What planting zone is ZIP code 91934?

ZIP code 91934 (Jacumba, CA) is in USDA hardiness zone 9b on the 2023 map: the coldest night of an average winter reaches 25 to 30 °F (−3.9 to −1.1 °C).

When is the last frost in Jacumba, CA?

The median last spring frost (32 °F) near 91934 is April 29; after June 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Campo Asos station.

When is the first frost in Jacumba, CA?

The median first fall frost near 91934 is November 1, giving a median frost-free growing season of 184 days.

When should I plant tomatoes in 91934?

Start tomato seeds indoors around Mar 4 – Mar 18 and set transplants outside around May 6 – May 20, one to three weeks after the median last frost.

How much rain and snow does 91934 get?

About 3.5 inches of precipitation a year (NOAA 1991–2020 normals, Ocotillo 2 station).

How hot do summers get in Jacumba, CA?

The average high peaks at 93 °F in August, with about 76 days a year at 90 °F or more.

What kind of soil does 91934 have?

The USDA soil survey maps Typic Haplocambids at the center of ZIP 91934: gravelly loamy coarse sand, well drained, pH about 8.0 (alkaline).

Did spring come early in Jacumba, CA in 2026?

Spring leaf-out near 91934 came on Jan 24 in 2026, 7 days earlier than the 1991–2020 average (Jan 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Jacumba, CA?

Intermediate onions: the longest day near 91934 is 14 h 18 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 91934 change?

Yes. The 2012 USDA map put 91934 in zone 8b; the 2023 map puts it in zone 9b. The newer map uses 1991–2020 data and more weather stations.