Last spring frost
Jun 15
Frost Dates for Alpine, AZ
First fall frost
Sep 21
Growing season
96 days
Hardiness zone
6b
In an average year around Alpine, AZ, the last spring frost (32°F) is about Jun 15 and the first fall frost is about Sep 21, giving roughly a 96-day growing season. To be safe most years, wait until Jun 2 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) | Jul 12 | Jun 28 | Jun 14 |
| Freeze (32°F) | Jun 30 | Jun 15 | Jun 2 |
| Hard (28°F) | Jun 19 | Jun 3 | May 19 |
| Severe (24°F) | Jun 6 | May 19 | May 2 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jul 12 | Jul 6 | Jul 2 | Jun 30 | Jun 28 | Jun 26 | Jun 22 | Jun 19 | Jun 14 |
| 32°F | Jun 30 | Jun 25 | Jun 21 | Jun 18 | Jun 15 | Jun 13 | Jun 9 | Jun 6 | Jun 2 |
| 28°F | Jun 19 | Jun 13 | Jun 9 | Jun 6 | Jun 3 | Jun 1 | May 29 | May 25 | May 19 |
| 24°F | Jun 6 | Jun 1 | May 27 | May 24 | May 19 | May 16 | May 12 | May 8 | May 2 |
| 20°F | May 21 | May 14 | May 10 | May 7 | May 4 | May 1 | Apr 27 | Apr 21 | Apr 14 |
| 16°F | May 3 | Apr 27 | Apr 22 | Apr 18 | Apr 12 | Apr 8 | Apr 3 | Mar 27 | Mar 19 |
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) | Aug 29 | Sep 10 | Sep 22 |
| Freeze (32°F) | Sep 7 | Sep 21 | Oct 1 |
| Hard (28°F) | Sep 16 | Sep 28 | Oct 11 |
| Severe (24°F) | Sep 25 | Oct 8 | Oct 23 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 29 | Sep 1 | Sep 4 | Sep 8 | Sep 10 | Sep 13 | Sep 15 | Sep 18 | Sep 22 |
| 32°F | Sep 7 | Sep 12 | Sep 16 | Sep 18 | Sep 21 | Sep 23 | Sep 25 | Sep 28 | Oct 1 |
| 28°F | Sep 16 | Sep 21 | Sep 24 | Sep 26 | Sep 28 | Oct 1 | Oct 4 | Oct 6 | Oct 11 |
| 24°F | Sep 25 | Sep 30 | Oct 2 | Oct 4 | Oct 8 | Oct 11 | Oct 15 | Oct 19 | Oct 23 |
| 20°F | Oct 5 | Oct 9 | Oct 14 | Oct 17 | Oct 21 | Oct 24 | Oct 27 | Oct 31 | Nov 4 |
| 16°F | Oct 17 | Oct 22 | Oct 27 | Oct 30 | Nov 2 | Nov 5 | Nov 9 | Nov 13 | Nov 18 |
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: Alpine, Az, about 1.9 miles away@if(!empty($station['elevation_ft'])), at 8,050 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 Alpine, AZ?
On average, the last spring frost (32°F) around Alpine, AZ is about Jun 15. In cooler years it can run later, so for a safer bet many gardeners wait until Jun 2.
When is the first frost in the fall?
The first fall frost around Alpine, AZ typically arrives about Sep 21. 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 Jun 15 on average, or Jun 2 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 96 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 85920 Planting calendar → Arizona frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026