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

Planting zone for 93453 — Santa Margarita, CA

ZIP code 93453 (Santa Margarita, San Luis Obispo County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is February 4 and the first fall frost December 4.

Where ZIP 93453 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.

Zone8b15 to 20 °F
Coldest night−9.4 to −6.7 °C
Last frostFeb 4
First frostDec 4
2012 zone9a

Was 9a on the 2012 map — half a zone colder now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 8b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Santa Margarita, 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 Santa Margarita, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 4median — 50% chance of a later frost
Safe for tender plantsMarch 31only 10% chance of frost after
First fall frostDecember 4median — 10% chance by Nov 14
Growing season301 daysfrost-free, median

A hard freeze (28 °F) usually ends around December 31 and returns around December 17.

From the NOAA station Twitchell Dam, CA — 19 miles away, elevation 581 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 93453

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Dec 24 – Jan 7
SpinachSow outdoors · Dec 24 – Jan 14
Broccoli, cabbageStart indoors · Nov 26 – Dec 10
Broccoli, cabbageTransplant · Jan 14 – Jan 28
Onion setsPlant outdoors · Jan 7 – Jan 21
PotatoesPlant outdoors · Jan 14 – Jan 28
LettuceSow outdoors · Jan 7 – Jan 21
Carrots, beetsSow outdoors · Jan 14 – Jan 28
TomatoesStart indoors · Dec 10 – Dec 24
TomatoesTransplant · Feb 11 – Feb 25
Peppers, eggplantStart indoors · Nov 26 – Dec 10
Peppers, eggplantTransplant · Feb 18 – Mar 4
BeansSow outdoors · Feb 11 – Feb 25
Sweet cornSow outdoors · Feb 11 – Feb 25
Cucumbers, squashSow outdoors · Feb 11 – Feb 25
Fall lettuce, spinachSow outdoors · Oct 9 – Oct 23
GarlicPlant cloves · Nov 20 – Dec 25
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 4) and first fall frost (Dec 4) 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 93453 came on Jan 19 — 11 days earlier than the 1991–2020 average (Jan 30).

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 Santa Margarita, CA

The soil mapped at the center of ZIP 93453 is Los Osos family — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up
pH7.0neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Los Osos-Nacimiento families association, 15 to 45 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 93453; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Santa Margarita, CA

Summer high78 °Faverage high, August
Winter low39 °Faverage low, December
Hot days26days a year at 90 °F or more
Freezing nights15nights a year at 32 °F or less
Growing degree days3,267base 50 °F — the season’s usable heat
Longest day14 h 32 mindaylight on June 21
Shortest day9 h 47 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation22.3 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°32 °FJanuary: average high 63 °F, low 41 °F 63°41° JanFebruary: average high 63 °F, low 43 °F 63°43° FebMarch: average high 65 °F, low 44 °F 65°44° MarApril: average high 68 °F, low 45 °F 68°45° AprMay: average high 70 °F, low 48 °F 70°48° MayJune: average high 75 °F, low 50 °F 75°50° JunJuly: average high 77 °F, low 53 °F 77°53° JulAugust: average high 78 °F, low 54 °F 78°54° AugSeptember: average high 78 °F, low 52 °F 78°52° SepOctober: average high 75 °F, low 49 °F 75°49° OctNovember: average high 68 °F, low 44 °F 68°44° NovDecember: average high 61 °F, low 39 °F 61°39° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 5.11 in precipitation 5.1 JanFebruary: 5.02 in precipitation 5.0 FebMarch: 3.89 in precipitation 3.9 MarApril: 1.40 in precipitation 1.4 AprMay: 0.52 in precipitation 0.5 MayJune: 0.06 in precipitation 0.1 JunJuly: 0.04 in precipitation 0.0 JulAugust: 0.01 in precipitation 0.0 AugSeptember: 0.09 in precipitation 0.1 SepOctober: 1.03 in precipitation 1.0 OctNovember: 1.55 in precipitation 1.6 NovDecember: 3.60 in precipitation 3.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Twitchell Dam, CA (19 mi away); precipitation: Salinas Dam, CA (17 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

934209b
Arroyo Grande, CA · 15 mi
934328b
Creston, CA · 22 mi
934549b
Santa Maria, CA · 22 mi
934569b
Santa Maria, CA · 23 mi
934579b
Santa Maria, CA · 23 mi
934589b
Santa Maria, CA · 25 mi
934559b
Santa Maria, CA · 31 mi
932549a
New Cuyama, CA · 31 mi

California planting zones →

Questions about 93453

What planting zone is ZIP code 93453?

ZIP code 93453 (Santa Margarita, CA) is in USDA hardiness zone 8b on the 2023 map: the coldest night of an average winter reaches 15 to 20 °F (−9.4 to −6.7 °C).

When is the last frost in Santa Margarita, CA?

The median last spring frost (32 °F) near 93453 is February 4; after March 31 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Twitchell Dam station.

When is the first frost in Santa Margarita, CA?

The median first fall frost near 93453 is December 4, giving a median frost-free growing season of 301 days.

When should I plant tomatoes in 93453?

Start tomato seeds indoors around Dec 10 – Dec 24 and set transplants outside around Feb 11 – Feb 25, one to three weeks after the median last frost.

How much rain and snow does 93453 get?

About 22.3 inches of precipitation a year (NOAA 1991–2020 normals, Salinas Dam station).

How hot do summers get in Santa Margarita, CA?

The average high peaks at 78 °F in August, with about 26 days a year at 90 °F or more.

What kind of soil does 93453 have?

The USDA soil survey maps Los Osos family at the center of ZIP 93453: clay loam, well drained, pH about 7.0 (neutral).

Did spring come early in Santa Margarita, CA in 2026?

Spring leaf-out near 93453 came on Jan 19 in 2026, 11 days earlier than the 1991–2020 average (Jan 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Santa Margarita, CA?

Intermediate onions: the longest day near 93453 is 14 h 32 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 93453 change?

Yes. The 2012 USDA map put 93453 in zone 9a; the 2023 map puts it in zone 8b. The newer map uses 1991–2020 data and more weather stations.