When is the last frost in San Jacinto, CA?

The average last spring frost (50% probability of 32°F) in San Jacinto is around January 31, based on NOAA/NCEI 1991–2020 normals at the San Jacinto, CA station (2.5 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in San Jacinto?

The average first fall frost in San Jacinto, CA is around December 10, giving roughly a 315-day frost-free growing season.

What planting zone is San Jacinto, CA?

San Jacinto is in USDA plant hardiness zone 9b (average annual extreme minimum temperature 25 to 30°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in San Jacinto?

In San Jacinto, CA the warmest month is August (avg high 96.5°F) and the coldest is December (avg low 39°F). It averages about 12.2″ of precipitation a year.

Home › California › San Jacinto

San Jacinto, CA Planting Calendar & Frost Dates

USDA hardiness zone 9b · ZIP 92583 · elevation 465′ · NOAA & USDA data

San Jacinto is in USDA hardiness zone 9b (winters can dip to 25 to 30°F), with a growing season of about 315 days between the average last spring frost (January 31) and first fall frost (December 10). The warmest month is August (avg high 96.5°F); the coldest is December (avg low 39°F). It averages 12.2″ of precipitation a year. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp 25 to 30°F

Last spring frost

January 31

avg (50% prob, 32°F)

First fall frost

December 10

avg (50% prob, 32°F)

Growing season

315 days

frost-free window

Warmest month

August

avg high 96.5°F

Month-by-month typical weather in San Jacinto

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at San Jacinto, CA (2.5 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)
January	65.8	40.1	52.9	2.7
February	65.8	41.7	53.7	2.8
March	70.2	45	57.6	1.7
April	74.4	47.9	61.2	0.8
May	80.4	53.3	66.8	0.5
June	88.7	57.6	73.2	0.1
July	95.1	63.6	79.3	0.2
August	96.5	64.3	80.4	0.1
September	91.8	60.7	76.3	0.3
October	82.3	52.7	67.5	0.5
November	72.7	44.4	58.5	0.8
December	65	39	52	1.9

What to plant when in San Jacinto

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: December 20 · Transplant out: February 7
Peppers	warm	Start seeds indoors: December 6 · Transplant out: February 14
Cucumbers	warm	Direct sow: February 7
Zucchini / squash	warm	Direct sow: February 7
Bush beans	warm	Direct sow: February 7
Sweet corn	warm	Direct sow: February 7
Basil	warm	Transplant out: February 7
Peas	cool	Sow (spring): December 27 · Sow (fall): October 15
Spinach	cool	Sow (spring): December 20 · Sow (fall): October 15
Lettuce	cool	Sow (spring): January 3 · Sow (fall): October 15
Kale	cool	Transplant (spring): January 10 · Sow (fall): October 1
Broccoli	cool	Transplant (spring): January 17
Carrots	cool	Sow (spring): January 10 · Sow (fall): October 1
Onions	cool	Transplant (spring): January 3
Potatoes	cool	Plant seed potatoes: January 17
Radishes	cool	Sow (spring): January 3 · Sow (fall): October 29

Dates are computed from San Jacinto's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

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Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

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Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — San Jacinto, CA, 2.5 mi (confidence: high). Monthly weather normals: San Jacinto, CA, 2.5 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.