Mesa, Arizona Frost Dates, Growing Season & Hardiness Zone

When is the last frost in Mesa?

A freeze isn't guaranteed every year. At E Mesa, NOAA puts the yearly chance of a 32°F night at 98.2%. Every date on this page is conditional: it describes only the years that reach 32°F.

When a freeze does come, the last 32°F night is typically by Feb 1, and 1 in 10 of those years has one after Feb 28. 36°F nights (frost possible on plants) happen in 100% of years and typically end around Feb 27. 28°F hard freezes happen in 70.1% of years.

Mesa has a long late-frost tail: 27 days separate the typical date (Feb 1) from the safer 1-in-10 date (Feb 28). If tender plants go out early, be ready to protect them on cold nights.

Cold nights don't end with the last freeze. In years with a freeze, the typical last 32°F night is Feb 1; the typical last 36°F night (frost possible on plants in low spots) comes around Feb 27, 26 days later. Frost can form on leaves on clear, calm nights even with the thermometer above freezing.

Is it too early to plant in Mesa?

Before Feb 1 the odds of another 32°F night are better than even; after Feb 28 they are about 1 in 10 or less.

Today's risk is computed in your browser from the same NOAA probability table, shown as the range between the two nearest NOAA probability levels.

When is the first frost in Mesa?

When a freeze does come, the first 32°F night is typically by Dec 10; in 1 in 10 of those years it comes as early as Nov 22. Look for the first 36°F night (frost possible on plants) around Nov 30. 28°F hard freezes happen in 70.1% of years.

Fall plantings are timed backward from first frost: Dec 10 typically, or Nov 22 if you want a cushion. See the planting calendar for each crop's date.

How long is Mesa's growing season?

In a typical year, Mesa gets 312 days between the last and first 32°F nights. About 1 year in 10, the season is shorter than 280 days.

With a season this long, you can grow many crops twice: once in spring and again for fall.

The station averages 8,239 growing degree days (base 50°F) a year. That number measures how much heat crops have to grow on.

How does Mesa's season compare?

Among the 3 Arizona cities with frost dates on this site, the typical frost-free season in Mesa (312 days) is the 2nd longest.

Nationwide, across the 56 cities with frost dates on this site, the typical frost-free season here outlasts the one in 48 of them and falls short of the one in 7.

Growing degree days (base 50°F)

Annual normal: 8,239 GDD (NOAA flag R, 14 years). Running total by the end of each month (sum of NOAA daily GDD normals, so the year-end total can differ slightly from the annual normal):

What growing zone is Mesa? (USDA 2023)

On the 2023 USDA map, Mesa is zone 9b–10a (25 to 35°F average coldest winter night). On the 2012 map, most of the city was 9b. Of the 18 city ZIPs listed in both tables, 3 moved up half a zone.

Zones: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed 2026-10-08. Shown as published in the ZIP tables; this page does not show a zone map. Not the official USDA Plant Hardiness Zone Map (official map: planthardiness.ars.usda.gov).

Does the new zone change Mesa's frost dates?

No. Hardiness zones are based only on the average coldest winter temperature. They say nothing about when spring and fall frosts happen. Mesa's frost dates come from NOAA's 1991–2020 frost probabilities, which did not change with the 2023 zone map. Use your zone to pick perennials that will survive winter, and your frost dates to time planting.

Why do Mesa frost dates differ between websites?

Some sources list Feb 12 for Mesa. That's the 30%-risk date: about 3 in 10 years with a freeze still have a 32°F night after it. Our headline date is Feb 1, the 50% (median) date.

We call Feb 28 the 'safer' date. It's the 10%-risk date: in about 1 in 10 years with a freeze, a 32°F night still comes after it.

Feb 27 is the typical (50%) date for a 36°F night (frost possible on plants), not a 32°F freeze. Any site that draws the line at 36°F will show later dates.

The choice of weather station matters too. The 8 stations within 25 miles of the city center that pass our quality rules give typical (50%) last 32°F frost dates from Jan 5 to Feb 13; see the table below.

Which weather station is this based on?

Station

E Mesa (NOAA USC00022782, COOP)

Distance

4.3 mi ENE of the city center

Elevation

1,518 ft; city center 1,330 ft (USGS), difference +188 ft

Record

NOAA completeness flag R, 15 of 30 years (1991–2020)

Confidence

Medium (rule)

Confidence: Medium. The station meets our quality rules, but its distance (4.3 mi) or elevation difference (+188 ft) is larger than ideal. Its frost statistics: NOAA flag R, 15 of 30 years.

Caveat: these frost statistics carry NOAA's 'R' (representative) flag. They're based on 15 of the 30 years in 1991–2020, with missing months filled in from surrounding stations. The nearest station with a full 'S' (standard) record is Phoenix Sky Harbor International Airport, 16.7 mi away, with a typical last frost of Jan 5.

Mesa planting dates at a glance

Balanced dates use the 30%-risk last-frost date as the anchor. The Mesa planting calendar has typical and safe dates, fall planting and a month-by-month list for 26 vegetables.

When to plant tomatoes in Mesa · Fall planting dates for Mesa

Frost dates near Mesa

All Arizona cities

Frequently asked questions

What is the average last frost date in Mesa?

Not every winter in Mesa freezes: NOAA puts the yearly chance of a 32°F night at E Mesa at 98.2%. In the years that do freeze, the typical (50%) last one is Feb 1, and only about 1 in 10 of those years has one after Feb 28.

When is the first frost in Mesa?

In years with a freeze, the first 32°F night typically arrives by Dec 10, and in about 1 in 10 of those years it comes as early as Nov 22. NOAA puts the yearly chance of a 32°F night at E Mesa at 98.2%.

What growing zone is Mesa, Arizona?

Zone 9b–10a. Most of Mesa was 9b on the 2012 map too, but 3 of 18 city ZIPs changed zone.

Is it too early to plant in Mesa?

If you plant frost-tender crops before Feb 1, a 32°F night after planting is more likely than not in years with a freeze. For planting days from Feb 1 to Feb 28, that risk falls from 50% to 10% of those years. In any given year, NOAA puts the chance of a 32°F night at E Mesa at 98.2%. Peas, lettuce and other cool-season crops can go in weeks earlier (see the planting calendar).

What temperature is a killing frost?

It depends on the crop. Tender plants such as tomatoes are killed by a light frost, which CSU Extension describes as 28–32°F; below 28°F is a heavy frost. We show NOAA odds for 36°F (frost possible on plants), 32°F (freeze, our headline) and 28°F (hard freeze).

Is first frost the same as first freeze?

Not exactly. A freeze is about the air reaching 32°F. Frost is ice on surfaces, which can form on calm, clear nights while the air is still a few degrees above freezing. The first 36°F night (frost possible on plants) in Mesa typically comes around Nov 30. Freezes don't come every year here: NOAA puts the yearly chance of a 32°F night at 98.2%, and in years that have one, the first typically arrives around Dec 10.

Download & sources

• Add Mesa frost & planting dates to your calendar (.ics, 2027)
• Printable planting calendar (PDF)
• How these numbers are calculated

Data: NOAA NCEI U.S. Climate Normals 1991–2020 (annual/seasonal and daily normals, station USC00022782); USDA Plant Hardiness Zone ZIP tables 2023 and 2012 by the PRISM Group, Oregon State University; Census 2020 ZIP/place relationship file; USGS elevation. Long-term odds, not a forecast. Figures and sentences are generated from these data by fixed rules; see the methodology. Last updated 2026-10-08.