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

Planting zone for 92040 — Lakeside, CA

ZIP code 92040 (Lakeside, San Diego County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F. The median last spring frost is March 19 and the first fall frost December 8.

Where ZIP 92040 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.

Zone10a30 to 35 °F
Coldest night−1.1 to 1.7 °C
Last frostMar 19
First frostDec 8
2012 zone10a

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 10a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Lakeside, 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 Lakeside, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 19median — 50% chance of a later frost
Safe for tender plantsJune 1only 10% chance of frost after
First fall frostDecember 8median — 10% chance by Oct 25
Growing season270 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 22 and returns around January 1.

From the NOAA station El Capitan Dam, CA — 5 miles away, elevation 600 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 92040

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 5 – Feb 19
SpinachSow outdoors · Feb 5 – Feb 26
Broccoli, cabbageStart indoors · Jan 8 – Jan 22
Broccoli, cabbageTransplant · Feb 26 – Mar 12
Onion setsPlant outdoors · Feb 19 – Mar 5
PotatoesPlant outdoors · Feb 26 – Mar 12
LettuceSow outdoors · Feb 19 – Mar 5
Carrots, beetsSow outdoors · Feb 26 – Mar 12
TomatoesStart indoors · Jan 22 – Feb 5
TomatoesTransplant · Mar 26 – Apr 9
Peppers, eggplantStart indoors · Jan 8 – Jan 22
Peppers, eggplantTransplant · Apr 2 – Apr 16
BeansSow outdoors · Mar 26 – Apr 9
Sweet cornSow outdoors · Mar 26 – Apr 9
Cucumbers, squashSow outdoors · Mar 26 – Apr 9
Fall lettuce, spinachSow outdoors · Oct 13 – Oct 27
GarlicPlant cloves · Nov 24 – Dec 29
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 19) and first fall frost (Dec 8) 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 92040 came on Jan 18 — 7 days earlier than the 1991–2020 average (Jan 25).

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 Lakeside, CA

The soil mapped at the center of ZIP 92040 is Vista — coarse sandy loam, well drained.

TextureCoarse sandy loamdrains and warms fast; dries out and needs more feeding
pH6.7neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter0.75%low — add compost
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Vista rocky coarse sandy loam, 15 to 30 percent slopes.

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 92040; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Lakeside, CA

Summer high97 °Faverage high, August
Winter low41 °Faverage low, January
Hot days121days a year at 90 °F or more
Freezing nights22nights a year at 32 °F or less
Growing degree days5,704base 50 °F — the season’s usable heat
Longest day14 h 19 mindaylight on June 21
Shortest day9 h 59 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation15.1 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 72 °F, low 41 °F 72°41° JanFebruary: average high 72 °F, low 41 °F 72°41° FebMarch: average high 74 °F, low 43 °F 74°43° MarApril: average high 79 °F, low 45 °F 79°45° AprMay: average high 83 °F, low 51 °F 83°51° MayJune: average high 90 °F, low 50 °F 90°50° JunJuly: average high 95 °F, low 56 °F 95°56° JulAugust: average high 97 °F, low 58 °F 97°58° AugSeptember: average high 94 °F, low 55 °F 94°55° SepOctober: average high 88 °F, low 51 °F 88°51° OctNovember: average high 79 °F, low 45 °F 79°45° NovDecember: average high 72 °F, low 41 °F 72°41° Dec

Precipitation by month inches

0″1″2″3″4″January: 2.86 in precipitation 2.9 JanFebruary: 3.56 in precipitation 3.6 FebMarch: 2.45 in precipitation 2.5 MarApril: 1.12 in precipitation 1.1 AprMay: 0.43 in precipitation 0.4 MayJune: 0.08 in precipitation 0.1 JunJuly: 0.10 in precipitation 0.1 JulAugust: 0.03 in precipitation 0.0 AugSeptember: 0.17 in precipitation 0.2 SepOctober: 0.72 in precipitation 0.7 OctNovember: 1.29 in precipitation 1.3 NovDecember: 2.29 in precipitation 2.3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: El Capitan Dam, CA (5 mi away); precipitation: Lakeside 2 E, CA (4 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.

9202110a
El Cajon, CA · 5 mi
9207210a
Santee, CA · 7 mi
9207110a
Santee, CA · 7 mi
9206410a
Poway, CA · 9 mi
9202210a
El Cajon, CA · 9 mi
919039b
Alpine, CA · 9 mi
9213110b
San Diego, CA · 9 mi
9202010a
El Cajon, CA · 9 mi

California planting zones →

Questions about 92040

What planting zone is ZIP code 92040?

ZIP code 92040 (Lakeside, CA) is in USDA hardiness zone 10a on the 2023 map: the coldest night of an average winter reaches 30 to 35 °F (−1.1 to 1.7 °C).

When is the last frost in Lakeside, CA?

The median last spring frost (32 °F) near 92040 is March 19; after June 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, El Capitan Dam station.

When is the first frost in Lakeside, CA?

The median first fall frost near 92040 is December 8, giving a median frost-free growing season of 270 days.

When should I plant tomatoes in 92040?

Start tomato seeds indoors around Jan 22 – Feb 5 and set transplants outside around Mar 26 – Apr 9, one to three weeks after the median last frost.

How much rain and snow does 92040 get?

About 15.1 inches of precipitation a year (NOAA 1991–2020 normals, Lakeside 2 E station).

How hot do summers get in Lakeside, CA?

The average high peaks at 97 °F in August, with about 121 days a year at 90 °F or more.

What kind of soil does 92040 have?

The USDA soil survey maps Vista at the center of ZIP 92040: coarse sandy loam, well drained, pH about 6.7 (neutral).

Did spring come early in Lakeside, CA in 2026?

Spring leaf-out near 92040 came on Jan 18 in 2026, 7 days earlier than the 1991–2020 average (Jan 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Lakeside, CA?

Intermediate onions: the longest day near 92040 is 14 h 19 min, so day-neutral types bulb best; long-day varieties may not bulb fully.