When is the last frost in Casa Grande, AZ?

The average last spring frost (50% probability of 32°F) in Casa Grande is around February 5, based on NOAA/NCEI 1991–2020 normals at the Casa Grande, AZ station (2.1 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 Casa Grande?

The average first fall frost in Casa Grande, AZ is around December 6, giving roughly a 305-day frost-free growing season.

What planting zone is Casa Grande, AZ?

Casa Grande is in USDA plant hardiness zone 9a (average annual extreme minimum temperature 20 to 25°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Casa Grande?

In Casa Grande, AZ the warmest month is July (avg high 106.8°F) and the coldest is December (avg low 38.4°F). It averages about 7.9″ of precipitation a year.

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Casa Grande, AZ Planting Calendar & Frost Dates

USDA hardiness zone 9a · ZIP 85130 · elevation 427′ · NOAA & USDA data

Casa Grande is in USDA hardiness zone 9a (winters can dip to 20 to 25°F), with a growing season of about 305 days between the average last spring frost (February 5) and first fall frost (December 6). The warmest month is July (avg high 106.8°F); the coldest is December (avg low 38.4°F). It averages 7.9″ 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 20 to 25°F

Last spring frost

February 5

avg (50% prob, 32°F)

First fall frost

December 6

avg (50% prob, 32°F)

Growing season

305 days

frost-free window

Warmest month

July

avg high 106.8°F

Month-by-month typical weather in Casa Grande

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Casa Grande, AZ (2.1 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)
January	68.7	39.1	53.9	0.8
February	72.6	41.5	57	1
March	79.9	47.2	63.6	0.8
April	87.5	53	70.3	0.2
May	96.4	60.4	78.4	0.2
June	105.8	69.9	87.9	0.2
July	106.8	78.1	92.5	0.9
August	105.3	77.3	91.3	1.5
September	100.4	70.7	85.5	0.7
October	90.7	56.9	73.8	0.5
November	77.5	45.3	61.4	0.4
December	67.6	38.4	53	0.7

What to plant when in Casa Grande

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: December 25 · Transplant out: February 12
Peppers	warm	Start seeds indoors: December 11 · Transplant out: February 19
Cucumbers	warm	Direct sow: February 12
Zucchini / squash	warm	Direct sow: February 12
Bush beans	warm	Direct sow: February 12
Sweet corn	warm	Direct sow: February 12
Basil	warm	Transplant out: February 12
Peas	cool	Sow (spring): January 1 · Sow (fall): October 11
Spinach	cool	Sow (spring): December 25 · Sow (fall): October 11
Lettuce	cool	Sow (spring): January 8 · Sow (fall): October 11
Kale	cool	Transplant (spring): January 15 · Sow (fall): September 27
Broccoli	cool	Transplant (spring): January 22
Carrots	cool	Sow (spring): January 15 · Sow (fall): September 27
Onions	cool	Transplant (spring): January 8
Potatoes	cool	Plant seed potatoes: January 22
Radishes	cool	Sow (spring): January 8 · Sow (fall): October 25

Dates are computed from Casa Grande'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 — Casa Grande, AZ, 2.1 mi (confidence: high). Monthly weather normals: Casa Grande, AZ, 2.1 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.