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

Planting zone for 93451 — San Miguel, CA

ZIP code 93451 (San Miguel, 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 14 and the first fall frost November 30.

Where ZIP 93451 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 14
First frostNov 30
2012 zone8b

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 8b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for San Miguel, 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 San Miguel, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 14median — 50% chance of a later frost
Safe for tender plantsMarch 8only 10% chance of frost after
First fall frostNovember 30median — 10% chance by Nov 15
Growing season292 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 16 and returns around December 16.

From the NOAA station Coalinga, CA — 18 miles away, elevation 669 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 93451

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 3 – Jan 17
SpinachSow outdoors · Jan 3 – Jan 24
Broccoli, cabbageStart indoors · Dec 6 – Dec 20
Broccoli, cabbageTransplant · Jan 24 – Feb 7
Onion setsPlant outdoors · Jan 17 – Jan 31
PotatoesPlant outdoors · Jan 24 – Feb 7
LettuceSow outdoors · Jan 17 – Jan 31
Carrots, beetsSow outdoors · Jan 24 – Feb 7
TomatoesStart indoors · Dec 20 – Jan 3
TomatoesTransplant · Feb 21 – Mar 7
Peppers, eggplantStart indoors · Dec 6 – Dec 20
Peppers, eggplantTransplant · Feb 28 – Mar 14
BeansSow outdoors · Feb 21 – Mar 7
Sweet cornSow outdoors · Feb 21 – Mar 7
Cucumbers, squashSow outdoors · Feb 21 – Mar 7
Fall lettuce, spinachSow outdoors · Oct 5 – Oct 19
GarlicPlant cloves · Nov 16 – Dec 21
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 14) and first fall frost (Nov 30) 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 93451 came on Jan 28 — 6 days earlier than the 1991–2020 average (Feb 3).

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 Miguel, CA

The soil mapped at the center of ZIP 93451 is Los Osos — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up
pH6.7neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Los Osos clay loam, 50 to 75 percent slopes, cool.

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 93451; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in San Miguel, CA

Summer high101 °Faverage high, July
Winter low37 °Faverage low, December
Hot days131days a year at 90 °F or more
Freezing nights22nights a year at 32 °F or less
Growing degree days6,062base 50 °F — the season’s usable heat
Longest day14 h 36 mindaylight on June 21
Shortest day9 h 43 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation8.2 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 60 °F, low 38 °F 60°38° JanFebruary: average high 65 °F, low 41 °F 65°41° FebMarch: average high 72 °F, low 45 °F 72°45° MarApril: average high 78 °F, low 49 °F 78°49° AprMay: average high 87 °F, low 56 °F 87°56° MayJune: average high 95 °F, low 63 °F 95°63° JunJuly: average high 101 °F, low 69 °F 101°69° JulAugust: average high 100 °F, low 67 °F 100°67° AugSeptember: average high 95 °F, low 61 °F 95°61° SepOctober: average high 83 °F, low 52 °F 83°52° OctNovember: average high 70 °F, low 42 °F 70°42° NovDecember: average high 60 °F, low 37 °F 60°37° Dec

Precipitation by month inches

0″1″2″January: 1.95 in precipitation 1.9 JanFebruary: 1.76 in precipitation 1.8 FebMarch: 1.53 in precipitation 1.5 MarApril: 0.37 in precipitation 0.4 AprMay: 0.32 in precipitation 0.3 MayJune: 0.11 in precipitation 0.1 JunJuly: 0.02 in precipitation 0.0 JulAugust: 0.01 in precipitation 0.0 AugSeptember: 0.06 in precipitation 0.1 SepOctober: 0.33 in precipitation 0.3 OctNovember: 0.50 in precipitation 0.5 NovDecember: 1.22 in precipitation 1.2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Coalinga, CA (18 mi away); precipitation: Coalinga, CA (18 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.

934479a
Paso Robles, CA · 14 mi
932109b
Coalinga, CA · 18 mi
934509a
San Ardo, CA · 18 mi
934469a
Paso Robles, CA · 21 mi
934269a
Bradley, CA · 24 mi
939549a
San Lucas, CA · 25 mi
934618b
Shandon, CA · 26 mi
932049b
Avenal, CA · 27 mi

California planting zones →

Questions about 93451

What planting zone is ZIP code 93451?

ZIP code 93451 (San Miguel, 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 San Miguel, CA?

The median last spring frost (32 °F) near 93451 is February 14; after March 8 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Coalinga station.

When is the first frost in San Miguel, CA?

The median first fall frost near 93451 is November 30, giving a median frost-free growing season of 292 days.

When should I plant tomatoes in 93451?

Start tomato seeds indoors around Dec 20 – Jan 3 and set transplants outside around Feb 21 – Mar 7, one to three weeks after the median last frost.

How much rain and snow does 93451 get?

About 8.2 inches of precipitation a year (NOAA 1991–2020 normals, Coalinga station).

How hot do summers get in San Miguel, CA?

The average high peaks at 101 °F in July, with about 131 days a year at 90 °F or more.

What kind of soil does 93451 have?

The USDA soil survey maps Los Osos at the center of ZIP 93451: clay loam, well drained, pH about 6.7 (neutral).

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

Spring leaf-out near 93451 came on Jan 28 in 2026, 6 days earlier than the 1991–2020 average (Feb 3), according to the USA National Phenology Network Spring Index.

What kind of onions grow in San Miguel, CA?

Intermediate onions: the longest day near 93451 is 14 h 36 min, so day-neutral types bulb best; long-day varieties may not bulb fully.