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

Planting zone for 93452 — San Simeon, CA

ZIP code 93452 (San Simeon, San Luis Obispo County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.

Where ZIP 93452 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 frostrare
First frostrare
2012 zone9b

Was 9b 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 10a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for San Simeon, 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 Hearst Castle, CA — 6 miles away, elevation 1,526 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 93452 came on Jan 19 — 7 days earlier than the 1991–2020 average (Jan 26).

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 Simeon, CA

The soil mapped at the center of ZIP 93452 is Lompico — loam, well drained.

TextureLoama good balance for most vegetables
pH6.7neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Lompico-McMullin loams, 30 to 75 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 93452; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in San Simeon, CA

Summer high78 °Faverage high, September
Winter low45 °Faverage low, February
Hot days15days a year at 90 °F or more
Freezing nights1nights a year at 32 °F or less
Growing degree days3,841base 50 °F — the season’s usable heat
Longest day14 h 35 mindaylight on June 21
Shortest day9 h 44 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation29.3 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°32 °FJanuary: average high 60 °F, low 47 °F 60°47° JanFebruary: average high 60 °F, low 45 °F 60°45° FebMarch: average high 62 °F, low 47 °F 62°47° MarApril: average high 65 °F, low 47 °F 65°47° AprMay: average high 69 °F, low 52 °F 69°52° MayJune: average high 73 °F, low 55 °F 73°55° JunJuly: average high 75 °F, low 57 °F 75°57° JulAugust: average high 77 °F, low 58 °F 77°58° AugSeptember: average high 78 °F, low 60 °F 78°60° SepOctober: average high 74 °F, low 56 °F 74°56° OctNovember: average high 66 °F, low 50 °F 66°50° NovDecember: average high 59 °F, low 46 °F 59°46° Dec

Precipitation by month inches

0″2″4″6″January: 5.96 in precipitation 6.0 JanFebruary: 6.15 in precipitation 6.2 FebMarch: 4.80 in precipitation 4.8 MarApril: 2.00 in precipitation 2.0 AprMay: 0.71 in precipitation 0.7 MayJune: 0.06 in precipitation 0.1 JunJuly: 0.08 in precipitation 0.1 JulAugust: 0.01 in precipitation 0.0 AugSeptember: 0.07 in precipitation 0.1 SepOctober: 1.11 in precipitation 1.1 OctNovember: 2.34 in precipitation 2.3 NovDecember: 6.05 in precipitation 6.0 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Hearst Castle, CA (6 mi away); precipitation: Hearst Castle, CA (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

9342810a
Cambria, CA · 15 mi
934269a
Bradley, CA · 15 mi
939329a
Lockwood, CA · 19 mi
9343010a
Cayucos, CA · 24 mi
9344310a
Morro Bay, CA · 34 mi
934239a
Atascadero, CA · 34 mi
934429b
Morro Bay, CA · 34 mi
9341210a
Los Osos, CA · 37 mi

California planting zones →

Questions about 93452

What planting zone is ZIP code 93452?

ZIP code 93452 (San Simeon, 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 93452 get?

About 29.3 inches of precipitation a year (NOAA 1991–2020 normals, Hearst Castle station).

How hot do summers get in San Simeon, CA?

The average high peaks at 78 °F in September, with about 15 days a year at 90 °F or more.

What kind of soil does 93452 have?

The USDA soil survey maps Lompico at the center of ZIP 93452: loam, well drained, pH about 6.7 (neutral).

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

Spring leaf-out near 93452 came on Jan 19 in 2026, 7 days earlier than the 1991–2020 average (Jan 26), according to the USA National Phenology Network Spring Index.

What kind of onions grow in San Simeon, CA?

Intermediate onions: the longest day near 93452 is 14 h 35 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 93452 change?

Yes. The 2012 USDA map put 93452 in zone 9b; the 2023 map puts it in zone 10a. The newer map uses 1991–2020 data and more weather stations.