Last spring frost
May 16
Frost Dates for Hard Rock, AZ
First fall frost
Oct 10
Growing season
147 days
Hardiness zone
7a
In an average year around Hard Rock, AZ, the last spring frost (32°F) is about May 16 and the first fall frost is about Oct 10, giving roughly a 147-day growing season. To be safe most years, wait until Apr 29 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 15 | Jun 1 | May 14 |
| Freeze (32°F) | Jun 5 | May 16 | Apr 29 |
| Hard (28°F) | May 20 | May 1 | Apr 14 |
| Severe (24°F) | May 8 | Apr 17 | Mar 28 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 15 | Jun 9 | Jun 6 | Jun 3 | Jun 1 | May 29 | May 24 | May 19 | May 14 |
| 32°F | Jun 5 | May 31 | May 25 | May 19 | May 16 | May 12 | May 8 | May 3 | Apr 29 |
| 28°F | May 20 | May 13 | May 9 | May 4 | May 1 | Apr 28 | Apr 24 | Apr 20 | Apr 14 |
| 24°F | May 8 | May 1 | Apr 26 | Apr 21 | Apr 17 | Apr 12 | Apr 8 | Apr 4 | Mar 28 |
| 20°F | Apr 24 | Apr 14 | Apr 8 | Apr 3 | Mar 29 | Mar 23 | Mar 18 | Mar 13 | Mar 6 |
| 16°F | Mar 31 | Mar 21 | Mar 15 | Mar 11 | Mar 7 | Mar 4 | Feb 28 | Feb 23 | Feb 13 |
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 22 | Oct 2 | Oct 15 |
| Freeze (32°F) | Sep 29 | Oct 10 | Oct 24 |
| Hard (28°F) | Oct 6 | Oct 20 | Nov 5 |
| Severe (24°F) | Oct 15 | Nov 1 | Nov 14 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 22 | Sep 25 | Sep 28 | Oct 1 | Oct 2 | Oct 5 | Oct 7 | Oct 10 | Oct 15 |
| 32°F | Sep 29 | Oct 2 | Oct 5 | Oct 7 | Oct 10 | Oct 13 | Oct 16 | Oct 19 | Oct 24 |
| 28°F | Oct 6 | Oct 11 | Oct 15 | Oct 17 | Oct 20 | Oct 24 | Oct 28 | Nov 1 | Nov 5 |
| 24°F | Oct 15 | Oct 20 | Oct 25 | Oct 29 | Nov 1 | Nov 4 | Nov 6 | Nov 10 | Nov 14 |
| 20°F | Oct 24 | Oct 31 | Nov 3 | Nov 7 | Nov 11 | Nov 13 | Nov 17 | Nov 19 | Nov 24 |
| 16°F | Nov 2 | Nov 10 | Nov 14 | Nov 17 | Nov 19 | Nov 22 | Nov 25 | Nov 28 | Dec 3 |
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: Keams Canyon, Az, about 23.8 miles away@if(!empty($station['elevation_ft'])), at 6,205 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 Hard Rock, AZ?
On average, the last spring frost (32°F) around Hard Rock, AZ is about May 16. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 29.
When is the first frost in the fall?
The first fall frost around Hard Rock, AZ typically arrives about Oct 10. 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 16 on average, or Apr 29 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 147 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 86039 Planting calendar → Arizona frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026