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

Planting zone for 93446 — Paso Robles, CA

ZIP code 93446 (Paso Robles, San Luis Obispo County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is March 15 and the first fall frost November 10.

Where ZIP 93446 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.

Zone9a20 to 25 °F
Coldest night−6.7 to −3.9 °C
Last frostMar 15
First frostNov 10
2012 zone8b

Was 8b 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 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Paso Robles, 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 Paso Robles, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 15median — 50% chance of a later frost
Safe for tender plantsApril 13only 10% chance of frost after
First fall frostNovember 10median — 10% chance by Oct 23
Growing season238 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 9 and returns around November 26.

From the NOAA station Paso Robles, CA — 3 miles away, elevation 732 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 93446

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 1 – Feb 15
SpinachSow outdoors · Feb 1 – Feb 22
Broccoli, cabbageStart indoors · Jan 4 – Jan 18
Broccoli, cabbageTransplant · Feb 22 – Mar 8
Onion setsPlant outdoors · Feb 15 – Mar 1
PotatoesPlant outdoors · Feb 22 – Mar 8
LettuceSow outdoors · Feb 15 – Mar 1
Carrots, beetsSow outdoors · Feb 22 – Mar 8
TomatoesStart indoors · Jan 18 – Feb 1
TomatoesTransplant · Mar 22 – Apr 5
Peppers, eggplantStart indoors · Jan 4 – Jan 18
Peppers, eggplantTransplant · Mar 29 – Apr 12
BeansSow outdoors · Mar 22 – Apr 5
Sweet cornSow outdoors · Mar 22 – Apr 5
Cucumbers, squashSow outdoors · Mar 22 – Apr 5
Fall lettuce, spinachSow outdoors · Sep 15 – Sep 29
GarlicPlant cloves · Oct 27 – Dec 1
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 15) and first fall frost (Nov 10) 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 93446 came on Jan 29 — about the same time as 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 Paso Robles, CA

The soil mapped at the center of ZIP 93446 is Linne — channery clay loam, well drained.

TextureChannery clay loamholds water and nutrients; slow to drain and warm up
pH8.2alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Linne-Calodo complex, 9 to 30 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 93446; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Paso Robles, CA

Summer high92 °Faverage high, August
Winter low33 °Faverage low, December
Hot days80days a year at 90 °F or more
Freezing nights54nights a year at 32 °F or less
Growing degree days3,887base 50 °F — the season’s usable heat
Longest day14 h 34 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
Precipitation15.3 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 62 °F, low 34 °F 62°34° JanFebruary: average high 64 °F, low 37 °F 64°37° FebMarch: average high 68 °F, low 40 °F 68°40° MarApril: average high 73 °F, low 41 °F 73°41° AprMay: average high 80 °F, low 46 °F 80°46° MayJune: average high 87 °F, low 50 °F 87°50° JunJuly: average high 91 °F, low 53 °F 91°53° JulAugust: average high 92 °F, low 53 °F 92°53° AugSeptember: average high 89 °F, low 50 °F 89°50° SepOctober: average high 81 °F, low 43 °F 81°43° OctNovember: average high 69 °F, low 37 °F 69°37° NovDecember: average high 61 °F, low 33 °F 61°33° Dec

Precipitation by month inches

0″1″2″3″4″January: 3.44 in precipitation 3.4 JanFebruary: 3.24 in precipitation 3.2 FebMarch: 2.84 in precipitation 2.8 MarApril: 0.81 in precipitation 0.8 AprMay: 0.36 in precipitation 0.4 MayJune: 0.04 in precipitation 0.0 JunJuly: 0.10 in precipitation 0.1 JulAugust: 0.02 in precipitation 0.0 AugSeptember: 0.08 in precipitation 0.1 SepOctober: 0.66 in precipitation 0.7 OctNovember: 1.16 in precipitation 1.2 NovDecember: 2.51 in precipitation 2.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Paso Robles, CA (3 mi away); precipitation: Paso Robles, CA (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

934479a
Paso Robles, CA · 7 mi
934659a
Templeton, CA · 8 mi
934229a
Atascadero, CA · 13 mi
934239a
Atascadero, CA · 16 mi
9343010a
Cayucos, CA · 18 mi
934328b
Creston, CA · 18 mi
934429b
Morro Bay, CA · 18 mi
934269a
Bradley, CA · 19 mi

All 2 ZIP codes in Paso Robles → · California planting zones →

Questions about 93446

What planting zone is ZIP code 93446?

ZIP code 93446 (Paso Robles, CA) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in Paso Robles, CA?

The median last spring frost (32 °F) near 93446 is March 15; after April 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Paso Robles station.

When is the first frost in Paso Robles, CA?

The median first fall frost near 93446 is November 10, giving a median frost-free growing season of 238 days.

When should I plant tomatoes in 93446?

Start tomato seeds indoors around Jan 18 – Feb 1 and set transplants outside around Mar 22 – Apr 5, one to three weeks after the median last frost.

How much rain and snow does 93446 get?

About 15.3 inches of precipitation a year (NOAA 1991–2020 normals, Paso Robles station).

How hot do summers get in Paso Robles, CA?

The average high peaks at 92 °F in August, with about 80 days a year at 90 °F or more.

What kind of soil does 93446 have?

The USDA soil survey maps Linne at the center of ZIP 93446: channery clay loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Paso Robles, CA in 2026?

Spring leaf-out near 93446 came on Jan 29 in 2026, about the same as the 1991–2020 average (Jan 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Paso Robles, CA?

Intermediate onions: the longest day near 93446 is 14 h 34 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 93446 change?

Yes. The 2012 USDA map put 93446 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.