When is the last frost in Antioch, CA?

The average last spring frost (50% probability of 32°F) in Antioch is around January 12, based on NOAA/NCEI 1991–2020 normals at the Antioch Pumping Plt #3, CA station (2.3 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 Antioch?

The average first fall frost in Antioch, CA is around December 19, giving roughly a 343-day frost-free growing season.

What planting zone is Antioch, CA?

Antioch 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 Antioch?

In Antioch, CA the warmest month is July (avg high 91.4°F) and the coldest is January (avg low 40.3°F). It averages about 12.6″ of precipitation a year.

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Antioch, CA Planting Calendar & Frost Dates

USDA hardiness zone 9b · ZIP 94531 · elevation 18′ · NOAA & USDA data

Antioch is in USDA hardiness zone 9b (winters can dip to 25 to 30°F), with a growing season of about 343 days between the average last spring frost (January 12) and first fall frost (December 19). The warmest month is July (avg high 91.4°F); the coldest is January (avg low 40.3°F). It averages 12.6″ 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 12

avg (50% prob, 32°F)

First fall frost

December 19

avg (50% prob, 32°F)

Growing season

343 days

frost-free window

Warmest month

July

avg high 91.4°F

Month-by-month typical weather in Antioch

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Antioch Pumping Plt #3, CA (2.3 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)
January	55.7	40.3	48	2.7
February	60.8	43.9	52.3	2.4
March	66.5	46.6	56.5	2
April	72.1	49.5	60.8	0.9
May	79	54.3	66.6	0.4
June	86.3	59	72.6	0.1
July	91.4	60.6	76	0
August	90.2	60.3	75.2	0
September	86.7	58.7	72.7	0.1
October	77.5	54.2	65.9	0.4
November	64.6	46.2	55.4	1.2
December	55.8	40.4	48.1	2.5

What to plant when in Antioch

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: December 1 · Transplant out: January 19
Peppers	warm	Start seeds indoors: November 17 · Transplant out: January 26
Cucumbers	warm	Direct sow: January 19
Zucchini / squash	warm	Direct sow: January 19
Bush beans	warm	Direct sow: January 19
Sweet corn	warm	Direct sow: January 19
Basil	warm	Transplant out: January 19
Peas	cool	Sow (spring): December 8 · Sow (fall): October 24
Spinach	cool	Sow (spring): December 1 · Sow (fall): October 24
Lettuce	cool	Sow (spring): December 15 · Sow (fall): October 24
Kale	cool	Transplant (spring): December 22 · Sow (fall): October 10
Broccoli	cool	Transplant (spring): December 29
Carrots	cool	Sow (spring): December 22 · Sow (fall): October 10
Onions	cool	Transplant (spring): December 15
Potatoes	cool	Plant seed potatoes: December 29
Radishes	cool	Sow (spring): December 15 · Sow (fall): November 7

Dates are computed from Antioch'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 — Antioch Pumping Plt #3, CA, 2.3 mi (confidence: high). Monthly weather normals: Antioch Pumping Plt #3, CA, 2.3 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.