Frost dates in Arizona

Across Arizona's 134 NOAA stations with a frost every year, the typical last spring frost ranges from February 4 at San Manuel (3,420 feet above sea level) to June 23 at Flagstaff 4 SW (7,130 feet above sea level). The middle station's date is April 11.

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Last frost across Arizona

The frost-free season runs from 81 days at Flagstaff 4 SW to 309 days at Temple Bar.

The station with the latest frost sits about 3,700 feet higher than the one with the earliest.

At 40 stations a freezing night doesn't come every winter, so the dates there apply only to the years that have one.

At 1 station, frost comes in fewer than 1 year in 10, too rarely for frost dates.

These are typical dates: in half of springs the last frost comes later. Each place's page, and each ZIP code lookup, also gives the late-year date, after which only 1 spring in 10 has a frost. That's the safer date for tender plants.

Frost dates for Arizona's larger places

Typical (1-in-2) dates. Each place's page has the early and late years, a planting calendar and a printable planner. Zones are for the ZIP code nearest each place's center. *Not every winter has a freeze here; the date is for the years that do.

Hardiness zones in Arizona

Arizona's 522 ZIP codes in the USDA list fall in zones 5b to 10a: 5b (under 1 percent), 6a (1 percent), 6b (5 percent), 7a (8 percent), 7b (3 percent), 8a (6 percent), 8b (11 percent), 9a (13 percent), 9b (39 percent) and 10a (14 percent). Compared with the 2012 map, 25 percent of them moved to a warmer half zone (6 by a full zone or more), 69 percent stayed the same and 29 moved to a colder one.

A hardiness zone is about the coldest night of winter, which decides which shrubs, trees and perennials survive. Frost dates are about spring and fall, which decide when to plant. You need both. Read more about what the zones mean and what changed in 2023.

Every NOAA station in Arizona

All 175 stations in Arizona with frost statistics in NOAA's 1991 to 2020 normals, from A to Z. Station names are usually a town, an airport, or a distance and direction from a town. Find one near you and at a similar elevation.

*Not every winter has a freeze at this station; the date is for the years that do.

Typical (1-in-2) dates at 32°F. For the early and late years, and a planting calendar built from your own dates, look up your ZIP code.