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

Planting zone for 91906 — Campo, CA

ZIP code 91906 (Campo, San Diego County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is April 30 and the first fall frost October 26.

Where ZIP 91906 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 30
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 Campo, 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 Campo, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 30median — 50% chance of a later frost
Safe for tender plantsJune 1only 10% chance of frost after
First fall frostOctober 26median — 10% chance by Sep 30
Growing season174 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 2 and returns around November 14.

From the NOAA station Campo, CA — 2 miles away, elevation 2,631 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 91906

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 19 – Apr 2
SpinachSow outdoors · Mar 19 – Apr 9
Broccoli, cabbageStart indoors · Feb 19 – Mar 5
Broccoli, cabbageTransplant · Apr 9 – Apr 23
Onion setsPlant outdoors · Apr 2 – Apr 16
PotatoesPlant outdoors · Apr 9 – Apr 23
LettuceSow outdoors · Apr 2 – Apr 16
Carrots, beetsSow outdoors · Apr 9 – Apr 23
TomatoesStart indoors · Mar 5 – Mar 19
TomatoesTransplant · May 7 – May 21
Peppers, eggplantStart indoors · Feb 19 – Mar 5
Peppers, eggplantTransplant · May 14 – May 28
BeansSow outdoors · May 7 – May 21
Sweet cornSow outdoors · May 7 – May 21
Cucumbers, squashSow outdoors · May 7 – May 21
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 30) 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 91906 came on Jan 24 — 9 days earlier than the 1991–2020 average (Feb 2).

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 Campo, CA

The soil mapped at the center of ZIP 91906 is Tollhouse — slightly decomposed plant material, somewhat excessively drained.

TextureSlightly decomposed plant materialtop layer
pH5.8moderately acidic; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter75%high
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Tollhouse coarse sandy loam, 5 to 35 percent slopes, eroded, very stony.

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 91906; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Campo, CA

Summer high95 °Faverage high, August
Winter low33 °Faverage low, December
Hot days97days a year at 90 °F or more
Freezing nights71nights a year at 32 °F or less
Growing degree days3,872base 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
Precipitation15.6 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 64 °F, low 35 °F 64°35° JanFebruary: average high 64 °F, low 35 °F 64°35° FebMarch: average high 68 °F, low 36 °F 68°36° MarApril: average high 73 °F, low 38 °F 73°38° AprMay: average high 79 °F, low 42 °F 79°42° MayJune: average high 88 °F, low 45 °F 88°45° JunJuly: average high 94 °F, low 53 °F 94°53° JulAugust: average high 95 °F, low 54 °F 95°54° AugSeptember: average high 90 °F, low 50 °F 90°50° SepOctober: average high 80 °F, low 43 °F 80°43° OctNovember: average high 71 °F, low 37 °F 71°37° NovDecember: average high 63 °F, low 33 °F 63°33° Dec

Precipitation by month inches

0″1″2″3″4″January: 3.09 in precipitation, 0.1 in snowfall 3.1 JanFebruary: 3.45 in precipitation 3.5 FebMarch: 2.28 in precipitation 2.3 MarApril: 1.04 in precipitation, 0.1 in snowfall 1.0 AprMay: 0.38 in precipitation 0.4 MayJune: 0.09 in precipitation 0.1 JunJuly: 0.29 in precipitation 0.3 JulAugust: 0.42 in precipitation 0.4 AugSeptember: 0.40 in precipitation 0.4 SepOctober: 0.67 in precipitation 0.7 OctNovember: 1.03 in precipitation 1.0 NovDecember: 2.44 in precipitation, 0.1 in snowfall 2.4 Dec

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

Nearby ZIP codes

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

919639a
Potrero, CA · 7 mi
919059a
Boulevard, CA · 10 mi
919809b
Tecate, CA · 10 mi
919879b
Tecate, CA · 10 mi
919628b
Pine Valley, CA · 13 mi
919318b
Guatay, CA · 14 mi
919488a
Mount Laguna, CA · 14 mi
919019b
Alpine, CA · 18 mi

California planting zones →

Questions about 91906

What planting zone is ZIP code 91906?

ZIP code 91906 (Campo, 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 Campo, CA?

The median last spring frost (32 °F) near 91906 is April 30; after June 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Campo station.

When is the first frost in Campo, CA?

The median first fall frost near 91906 is October 26, giving a median frost-free growing season of 174 days.

When should I plant tomatoes in 91906?

Start tomato seeds indoors around Mar 5 – Mar 19 and set transplants outside around May 7 – May 21, one to three weeks after the median last frost.

How much rain and snow does 91906 get?

About 15.6 inches of precipitation a year (NOAA 1991–2020 normals, Campo station).

How hot do summers get in Campo, CA?

The average high peaks at 95 °F in August, with about 97 days a year at 90 °F or more.

What kind of soil does 91906 have?

The USDA soil survey maps Tollhouse at the center of ZIP 91906: slightly decomposed plant material, somewhat excessively drained, pH about 5.8 (moderately acidic).

Did spring come early in Campo, CA in 2026?

Spring leaf-out near 91906 came on Jan 24 in 2026, 9 days earlier than the 1991–2020 average (Feb 2), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Campo, CA?

Intermediate onions: the longest day near 91906 is 14 h 18 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 91906 change?

Yes. The 2012 USDA map put 91906 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.