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

Planting zone for 92079 — San Marcos, CA

ZIP code 92079 (San Marcos, San Diego County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.

Where ZIP 92079 is

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 frostrare
First frostrare
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 San Marcos, 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

A 32 °F frost doesn't happen here in most winters. At the nearest station (NOAA station Escondido #2, CA — 5 miles away, elevation 600 ft) the median growing season is 365 days. When frost does come, it is a midwinter night or two; cover tender plants when a freeze is forecast.

Frost data: NOAA NCEI U.S. Climate Normals 1991–2020.

When spring arrived in 2026

In 2026, spring leaf-out near 92079 came on Jan 17 — 5 days earlier than the 1991–2020 average (Jan 22).

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 San Marcos, CA

The soil mapped at the center of ZIP 92079 is Placentia — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding
pH6.0slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.25%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Placentia sandy loam, 2 to 9 percent slopes, warm MAAT, MLRA 19.

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 92079; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in San Marcos, CA

Summer high89 °Faverage high, August
Winter low44 °Faverage low, December
Hot days54days a year at 90 °F or more
Freezing nights2nights a year at 32 °F or less
Growing degree days5,796base 50 °F — the season’s usable heat
Longest day14 h 21 mindaylight on June 21
Shortest day9 h 57 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation13.9 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°32 °FJanuary: average high 69 °F, low 45 °F 69°45° JanFebruary: average high 69 °F, low 46 °F 69°46° FebMarch: average high 71 °F, low 49 °F 71°49° MarApril: average high 74 °F, low 52 °F 74°52° AprMay: average high 77 °F, low 56 °F 77°56° MayJune: average high 82 °F, low 60 °F 82°60° JunJuly: average high 87 °F, low 64 °F 87°64° JulAugust: average high 89 °F, low 65 °F 89°65° AugSeptember: average high 87 °F, low 63 °F 87°63° SepOctober: average high 81 °F, low 57 °F 81°57° OctNovember: average high 75 °F, low 49 °F 75°49° NovDecember: average high 68 °F, low 44 °F 68°44° Dec

Precipitation by month inches

0″1″2″3″4″January: 2.34 in precipitation 2.3 JanFebruary: 3.30 in precipitation 3.3 FebMarch: 2.15 in precipitation 2.1 MarApril: 1.29 in precipitation 1.3 AprMay: 0.39 in precipitation 0.4 MayJune: 0.12 in precipitation 0.1 JunJuly: 0.05 in precipitation 0.1 JulAugust: 0.01 in precipitation 0.0 AugSeptember: 0.10 in precipitation 0.1 SepOctober: 0.76 in precipitation 0.8 OctNovember: 0.92 in precipitation 0.9 NovDecember: 2.45 in precipitation 2.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Escondido #2, CA (5 mi away); precipitation: San Marcos 2.5 Ene, CA (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 10a.

9209610a
San Marcos, CA · 1 mi
9207810a
San Marcos, CA · 2 mi
9206910a
San Marcos, CA · 2 mi
9208110a
Vista, CA · 5 mi
9202910a
Escondido, CA · 5 mi
9203010a
Escondido, CA · 5 mi
9203310a
Escondido, CA · 5 mi
9204610a
Escondido, CA · 5 mi

All 4 ZIP codes in San Marcos → · California planting zones →

Questions about 92079

What planting zone is ZIP code 92079?

ZIP code 92079 (San Marcos, 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).

How much rain and snow does 92079 get?

About 13.9 inches of precipitation a year (NOAA 1991–2020 normals, San Marcos 2.5 Ene station).

How hot do summers get in San Marcos, CA?

The average high peaks at 89 °F in August, with about 54 days a year at 90 °F or more.

What kind of soil does 92079 have?

The USDA soil survey maps Placentia at the center of ZIP 92079: sandy loam, well drained, pH about 6.0 (slightly acidic).

Did spring come early in San Marcos, CA in 2026?

Spring leaf-out near 92079 came on Jan 17 in 2026, 5 days earlier than the 1991–2020 average (Jan 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in San Marcos, CA?

Intermediate onions: the longest day near 92079 is 14 h 21 min, so day-neutral types bulb best; long-day varieties may not bulb fully.