When is the last frost in Surprise, AZ?

The average last spring frost (50% probability of 32°F) in Surprise is around January 20, based on NOAA/NCEI 1991–2020 normals at the Youngtown, AZ station (6.4 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 Surprise?

The average first fall frost in Surprise, AZ is around December 15, giving roughly a 331-day frost-free growing season.

What planting zone is Surprise, AZ?

Surprise 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 Surprise?

In Surprise, AZ the warmest month is July (avg high 104.9°F) and the coldest is December (avg low 40.2°F). It averages about 8.3″ of precipitation a year.

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Surprise, AZ Planting Calendar & Frost Dates

USDA hardiness zone 9b · ZIP 85374 · elevation 346′ · NOAA & USDA data

Surprise is in USDA hardiness zone 9b (winters can dip to 25 to 30°F), with a growing season of about 331 days between the average last spring frost (January 20) and first fall frost (December 15). The warmest month is July (avg high 104.9°F); the coldest is December (avg low 40.2°F). It averages 8.3″ 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 20

avg (50% prob, 32°F)

First fall frost

December 15

avg (50% prob, 32°F)

Growing season

331 days

frost-free window

Warmest month

July

avg high 104.9°F

Month-by-month typical weather in Surprise

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Youngtown, AZ (6.4 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)
January	65.4	41.1	53.3	1
February	68.9	43.8	56.4	1.3
March	76.5	48.9	62.7	1
April	84.1	54.8	69.5	0.3
May	92.9	63.6	78.3	0.1
June	102.2	72.2	87.2	0
July	104.9	79.7	92.3	0.8
August	103.6	79.2	91.4	1
September	98.4	72.5	85.4	0.7
October	87	59.5	73.2	0.6
November	73.9	47.7	60.8	0.6
December	63.8	40.2	52	0.9

What to plant when in Surprise

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: December 9 · Transplant out: January 27
Peppers	warm	Start seeds indoors: November 25 · Transplant out: February 3
Cucumbers	warm	Direct sow: January 27
Zucchini / squash	warm	Direct sow: January 27
Bush beans	warm	Direct sow: January 27
Sweet corn	warm	Direct sow: January 27
Basil	warm	Transplant out: January 27
Peas	cool	Sow (spring): December 16 · Sow (fall): October 20
Spinach	cool	Sow (spring): December 9 · Sow (fall): October 20
Lettuce	cool	Sow (spring): December 23 · Sow (fall): October 20
Kale	cool	Transplant (spring): December 30 · Sow (fall): October 6
Broccoli	cool	Transplant (spring): January 6
Carrots	cool	Sow (spring): December 30 · Sow (fall): October 6
Onions	cool	Transplant (spring): December 23
Potatoes	cool	Plant seed potatoes: January 6
Radishes	cool	Sow (spring): December 23 · Sow (fall): November 3

Dates are computed from Surprise'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 — Youngtown, AZ, 6.4 mi (confidence: high). Monthly weather normals: Youngtown, AZ, 6.4 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.