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

Planting zone for San Jacinto, CA

San Jacinto, CA is in USDA zone 9b across its 3 ZIP codes. The median last spring frost is January 31 and the first fall frost December 10.

San Jacinto on the zone map

Outlined: its 2 ZIP code areas · 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
ZIP codes3
Last frostJan 31
First frostDec 10
Growing season315 days

9b 3 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for San Jacinto, 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 Jacinto, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostJanuary 31median — 50% chance of a later frost
Safe for tender plantsFebruary 28only 10% chance of frost after
First fall frostDecember 10median — 10% chance by Nov 22
Growing season315 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 3 and returns around December 21.

From the NOAA station San Jacinto, CA, elevation 1,526 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 San Jacinto

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Dec 20 – Jan 3
SpinachSow outdoors · Dec 20 – Jan 10
Broccoli, cabbageStart indoors · Nov 22 – Dec 6
Broccoli, cabbageTransplant · Jan 10 – Jan 24
Onion setsPlant outdoors · Jan 3 – Jan 17
PotatoesPlant outdoors · Jan 10 – Jan 24
LettuceSow outdoors · Jan 3 – Jan 17
Carrots, beetsSow outdoors · Jan 10 – Jan 24
TomatoesStart indoors · Dec 6 – Dec 20
TomatoesTransplant · Feb 7 – Feb 21
Peppers, eggplantStart indoors · Nov 22 – Dec 6
Peppers, eggplantTransplant · Feb 14 – Feb 28
BeansSow outdoors · Feb 7 – Feb 21
Sweet cornSow outdoors · Feb 7 – Feb 21
Cucumbers, squashSow outdoors · Feb 7 – Feb 21
Fall lettuce, spinachSow outdoors · Oct 15 – Oct 29
GarlicPlant cloves · Nov 26 – Dec 31
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jan 31) and first fall frost (Dec 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 92581 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 Jacinto, CA

The soil mapped at the center of ZIP 92581 is Metz — loamy sand, somewhat excessively drained.

TextureLoamy sanddrains and warms fast; dries out and needs more feeding
pH7.5slightly alkaline; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter0.75%low — add compost
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Metz loamy fine sand, gravelly sand substratum, 0 to 5 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 92581; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in San Jacinto, CA

Summer high97 °Faverage high, August
Winter low39 °Faverage low, December
Hot days120days a year at 90 °F or more
Freezing nights15nights a year at 32 °F or less
Growing degree days5,606base 50 °F — the season’s usable heat
Longest day14 h 24 mindaylight on June 21
Shortest day9 h 54 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation12.2 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 66 °F, low 40 °F 66°40° JanFebruary: average high 66 °F, low 42 °F 66°42° FebMarch: average high 70 °F, low 45 °F 70°45° MarApril: average high 74 °F, low 48 °F 74°48° AprMay: average high 80 °F, low 53 °F 80°53° MayJune: average high 89 °F, low 58 °F 89°58° JunJuly: average high 95 °F, low 64 °F 95°64° JulAugust: average high 97 °F, low 64 °F 97°64° AugSeptember: average high 92 °F, low 61 °F 92°61° SepOctober: average high 82 °F, low 53 °F 82°53° OctNovember: average high 73 °F, low 44 °F 73°44° NovDecember: average high 65 °F, low 39 °F 65°39° Dec

Precipitation by month inches

0″1″2″3″January: 2.66 in precipitation 2.7 JanFebruary: 2.76 in precipitation 2.8 FebMarch: 1.69 in precipitation 1.7 MarApril: 0.79 in precipitation 0.8 AprMay: 0.47 in precipitation 0.5 MayJune: 0.07 in precipitation 0.1 JunJuly: 0.20 in precipitation 0.2 JulAugust: 0.12 in precipitation 0.1 AugSeptember: 0.26 in precipitation 0.3 SepOctober: 0.54 in precipitation 0.5 OctNovember: 0.77 in precipitation 0.8 NovDecember: 1.87 in precipitation 1.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: San Jacinto, CA (within 1 mile); precipitation: San Jacinto, CA (within 1 mile). Daylight is calculated from latitude.

ZIP codes in San Jacinto

925819b
25 to 30 °F
925829b
25 to 30 °F
925839b
25 to 30 °F

California planting zones →

Questions about San Jacinto

What planting zone is San Jacinto, CA?

San Jacinto, CA is in USDA hardiness zone 9b on the 2023 map (9b: 25 to 30 °F).

When is the last frost in San Jacinto, CA?

The median last spring frost is January 31 and the median first fall frost is December 10 (NOAA 1991–2020 normals, San Jacinto station).

When can I plant a garden in San Jacinto, CA?

Cool-season crops like peas and spinach go in around Dec 20 – Jan 10; tomatoes, peppers, beans and squash after about Feb 7, once frost risk has passed.

What kind of onions grow in San Jacinto, CA?

Intermediate onions: the longest day is 14 h 24 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

How much rain and snow does San Jacinto, CA get?

About 12.2 inches of precipitation a year (NOAA 1991–2020 normals).