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

Planting zone for 93407 — San Luis Obispo, CA

ZIP code 93407 (San Luis Obispo, San Luis Obispo County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F.

Where ZIP 93407 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.

Zone9b25 to 30 °F
Coldest night−3.9 to −1.1 °C
Last frostrare
First frostrare
2012 zone9b

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 9b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for San Luis Obispo, 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 San Luis Obispo Poly, CA — within 1 mile, elevation 308 ft) the median growing season is 349 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 93407 came on Jan 19 — 6 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 San Luis Obispo, CA

The soil mapped at the center of ZIP 93407 is Salinas — silty clay loam, well drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH8.0alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Salinas silty clay loam, 0 to 2 percent slopes, MLRA 14.

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 93407; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in San Luis Obispo, CA

Summer high80 °Faverage high, August
Winter low44 °Faverage low, January
Hot days19days a year at 90 °F or more
Freezing nights3nights a year at 32 °F or less
Growing degree days3,929base 50 °F — the season’s usable heat
Longest day14 h 32 mindaylight on June 21
Shortest day9 h 46 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation22.4 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°32 °FJanuary: average high 65 °F, low 44 °F 65°44° JanFebruary: average high 65 °F, low 44 °F 65°44° FebMarch: average high 67 °F, low 46 °F 67°46° MarApril: average high 69 °F, low 47 °F 69°47° AprMay: average high 72 °F, low 49 °F 72°49° MayJune: average high 76 °F, low 52 °F 76°52° JunJuly: average high 78 °F, low 54 °F 78°54° JulAugust: average high 80 °F, low 55 °F 80°55° AugSeptember: average high 80 °F, low 54 °F 80°54° SepOctober: average high 78 °F, low 52 °F 78°52° OctNovember: average high 71 °F, low 47 °F 71°47° NovDecember: average high 64 °F, low 44 °F 64°44° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 5.07 in precipitation 5.1 JanFebruary: 4.92 in precipitation 4.9 FebMarch: 3.89 in precipitation 3.9 MarApril: 1.38 in precipitation 1.4 AprMay: 0.51 in precipitation 0.5 MayJune: 0.13 in precipitation 0.1 JunJuly: 0.07 in precipitation 0.1 JulAugust: 0.01 in precipitation 0.0 AugSeptember: 0.11 in precipitation 0.1 SepOctober: 0.76 in precipitation 0.8 OctNovember: 1.98 in precipitation 2.0 NovDecember: 3.59 in precipitation 3.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: San Luis Obispo Poly, CA (within 1 mile); precipitation: San Luis Obispo Poly, CA (within 1 mile). 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.

934109b
San Luis Obispo, CA · <1 mi
9340310a
San Luis Obispo, CA · 2 mi
9340610a
San Luis Obispo, CA · 2 mi
934099b
San Luis Obispo, CA · 2 mi
9340810a
San Luis Obispo, CA · 3 mi
934059b
San Luis Obispo, CA · 4 mi
934019b
San Luis Obispo, CA · 6 mi
9341210a
Los Osos, CA · 9 mi

All 8 ZIP codes in San Luis Obispo → · California planting zones →

Questions about 93407

What planting zone is ZIP code 93407?

ZIP code 93407 (San Luis Obispo, CA) is in USDA hardiness zone 9b on the 2023 map: the coldest night of an average winter reaches 25 to 30 °F (−3.9 to −1.1 °C).

How much rain and snow does 93407 get?

About 22.4 inches of precipitation a year (NOAA 1991–2020 normals, San Luis Obispo Poly station).

How hot do summers get in San Luis Obispo, CA?

The average high peaks at 80 °F in August, with about 19 days a year at 90 °F or more.

What kind of soil does 93407 have?

The USDA soil survey maps Salinas at the center of ZIP 93407: silty clay loam, well drained, pH about 8.0 (alkaline).

Did spring come early in San Luis Obispo, CA in 2026?

Spring leaf-out near 93407 came on Jan 19 in 2026, 6 days earlier than the 1991–2020 average (Jan 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in San Luis Obispo, CA?

Intermediate onions: the longest day near 93407 is 14 h 32 min, so day-neutral types bulb best; long-day varieties may not bulb fully.