Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 91905 — Boulevard, CA

ZIP code 91905 (Boulevard, San Diego County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is April 29 and the first fall frost November 1.

Where ZIP 91905 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 29

First frostNov 1

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 Boulevard, 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 Boulevard, 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 — 10 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 91905

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 91905 came on Jan 21 — 13 days earlier than the 1991–2020 average (Feb 3).

average
Feb 32026
Jan 21

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 Boulevard, CA

The soil mapped at the center of ZIP 91905 is La Posta — loamy coarse sand, somewhat excessively drained.

TextureLoamy coarse sanddrains and warms fast; dries out and needs more feeding

pH6.7neutral; most vegetables like 6.0–7.0

DrainageSomewhat excessively drainednatural drainage class

Organic matter2%moderate

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: La Posta loamy coarse sand, 5 to 30 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 91905; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Boulevard, 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

Precipitation14.8 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Campo Asos, CA (10 mi away); precipitation: Boulevard 4.4 Wsw, CA (3 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.

Mount Laguna, CA · 16 mi

919639a

Potrero, CA · 17 mi

919628b

Pine Valley, CA · 17 mi

California planting zones →

Questions about 91905

What planting zone is ZIP code 91905?

ZIP code 91905 (Boulevard, 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 Boulevard, CA?

The median last spring frost (32 °F) near 91905 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 Boulevard, CA?

The median first fall frost near 91905 is November 1, giving a median frost-free growing season of 184 days.

When should I plant tomatoes in 91905?

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 91905 get?

About 14.8 inches of precipitation a year (NOAA 1991–2020 normals, Boulevard 4.4 Wsw station).

How hot do summers get in Boulevard, 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 91905 have?

The USDA soil survey maps La Posta at the center of ZIP 91905: loamy coarse sand, somewhat excessively drained, pH about 6.7 (neutral).

Did spring come early in Boulevard, CA in 2026?

Spring leaf-out near 91905 came on Jan 21 in 2026, 13 days earlier than the 1991–2020 average (Feb 3), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Boulevard, CA?

Intermediate onions: the longest day near 91905 is 14 h 18 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 91905 change?

Yes. The 2012 USDA map put 91905 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.