Last spring frost
May 6
Frost Dates for Alma, AZ
First fall frost
Oct 18
Growing season
164 days
Hardiness zone
8a
In an average year around Alma, AZ, the last spring frost (32°F) is about May 6 and the first fall frost is about Oct 18, giving roughly a 164-day growing season. To be safe most years, wait until Apr 21 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Jun 5 | May 21 | May 5 |
| Freeze (32°F) | May 20 | May 6 | Apr 21 |
| Hard (28°F) | May 7 | Apr 21 | Apr 3 |
| Severe (24°F) | Apr 20 | Mar 31 | Mar 9 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 5 | Jun 1 | May 29 | May 24 | May 21 | May 17 | May 15 | May 11 | May 5 |
| 32°F | May 20 | May 16 | May 12 | May 9 | May 6 | May 3 | Apr 30 | Apr 28 | Apr 21 |
| 28°F | May 7 | May 2 | Apr 29 | Apr 25 | Apr 21 | Apr 17 | Apr 13 | Apr 9 | Apr 3 |
| 24°F | Apr 20 | Apr 12 | Apr 7 | Apr 3 | Mar 31 | Mar 27 | Mar 21 | Mar 16 | Mar 9 |
| 20°F | Apr 1 | Mar 23 | Mar 16 | Mar 11 | Mar 7 | Mar 2 | Feb 27 | Feb 21 | Feb 12 |
| 16°F | Mar 7 | Feb 28 | Feb 23 | Feb 17 | Feb 11 | Feb 4 | Jan 31 | Jan 24 | Jan 15 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Sep 27 | Oct 9 | Oct 20 |
| Freeze (32°F) | Oct 7 | Oct 18 | Oct 30 |
| Hard (28°F) | Oct 13 | Oct 28 | Nov 10 |
| Severe (24°F) | Oct 23 | Nov 7 | Nov 23 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 27 | Oct 1 | Oct 4 | Oct 6 | Oct 9 | Oct 11 | Oct 13 | Oct 17 | Oct 20 |
| 32°F | Oct 7 | Oct 10 | Oct 14 | Oct 16 | Oct 18 | Oct 21 | Oct 23 | Oct 27 | Oct 30 |
| 28°F | Oct 13 | Oct 19 | Oct 22 | Oct 26 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 10 |
| 24°F | Oct 23 | Oct 28 | Nov 1 | Nov 4 | Nov 7 | Nov 11 | Nov 14 | Nov 18 | Nov 23 |
| 20°F | Nov 1 | Nov 6 | Nov 12 | Nov 16 | Nov 20 | Nov 24 | Nov 28 | Dec 1 | Dec 5 |
| 16°F | Nov 16 | Nov 23 | Nov 27 | Dec 1 | Dec 4 | Dec 9 | Dec 14 | Dec 19 | Dec 28 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Glenwood, Nm, about 19.4 miles away@if(!empty($station['elevation_ft'])), at 4,725 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Alma, AZ?
On average, the last spring frost (32°F) around Alma, AZ is about May 6. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 21.
When is the first frost in the fall?
The first fall frost around Alma, AZ typically arrives about Oct 18. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around May 6 on average, or Apr 21 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 164 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 85922 Planting calendar → Arizona frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026