Last spring frost
May 1
Frost Dates for Sun Valley, AZ
First fall frost
Oct 20
Growing season
169 days
Hardiness zone
7a
In an average year around Sun Valley, AZ, the last spring frost (32°F) is about May 1 and the first fall frost is about Oct 20, giving roughly a 169-day growing season. To be safe most years, wait until Apr 18 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) | May 30 | May 13 | Apr 30 |
| Freeze (32°F) | May 16 | May 1 | Apr 18 |
| Hard (28°F) | May 4 | Apr 19 | Apr 2 |
| Severe (24°F) | Apr 21 | Apr 2 | Mar 10 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 30 | May 24 | May 19 | May 16 | May 13 | May 10 | May 7 | May 3 | Apr 30 |
| 32°F | May 16 | May 11 | May 7 | May 4 | May 1 | Apr 30 | Apr 26 | Apr 23 | Apr 18 |
| 28°F | May 4 | Apr 29 | Apr 25 | Apr 22 | Apr 19 | Apr 16 | Apr 11 | Apr 7 | Apr 2 |
| 24°F | Apr 21 | Apr 14 | Apr 9 | Apr 5 | Apr 2 | Mar 29 | Mar 22 | Mar 17 | Mar 10 |
| 20°F | Apr 4 | Mar 28 | Mar 20 | Mar 15 | Mar 11 | Mar 7 | Mar 4 | Feb 27 | Feb 19 |
| 16°F | Mar 16 | Mar 10 | Mar 5 | Mar 1 | Feb 25 | Feb 20 | Feb 14 | Feb 7 | Jan 28 |
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 10 | Oct 23 |
| Freeze (32°F) | Oct 6 | Oct 20 | Nov 3 |
| Hard (28°F) | Oct 14 | Oct 30 | Nov 12 |
| Severe (24°F) | Oct 25 | Nov 9 | Nov 22 |
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 7 | Oct 10 | Oct 13 | Oct 15 | Oct 19 | Oct 23 |
| 32°F | Oct 6 | Oct 10 | Oct 14 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Oct 29 | Nov 3 |
| 28°F | Oct 14 | Oct 21 | Oct 25 | Oct 28 | Oct 30 | Nov 2 | Nov 5 | Nov 8 | Nov 12 |
| 24°F | Oct 25 | Oct 30 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 18 | Nov 22 |
| 20°F | Nov 2 | Nov 7 | Nov 11 | Nov 15 | Nov 17 | Nov 20 | Nov 23 | Nov 26 | Dec 1 |
| 16°F | Nov 10 | Nov 15 | Nov 19 | Nov 23 | Nov 26 | Nov 29 | Dec 1 | Dec 5 | Dec 11 |
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: Painted Desert Np, Az, about 3.6 miles away@if(!empty($station['elevation_ft'])), at 5,760 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 Sun Valley, AZ?
On average, the last spring frost (32°F) around Sun Valley, AZ is about May 1. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 18.
When is the first frost in the fall?
The first fall frost around Sun Valley, AZ typically arrives about Oct 20. 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 1 on average, or Apr 18 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 169 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 86028 Planting calendar → Arizona frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026