Last spring frost
Apr 21
Frost Dates for San Simon, AZ
First fall frost
Oct 27
Growing season
188 days
Hardiness zone
8a
In an average year around San Simon, AZ, the last spring frost (32°F) is about Apr 21 and the first fall frost is about Oct 27, giving roughly a 188-day growing season. To be safe most years, wait until Apr 5 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 20 | May 5 | Apr 21 |
| Freeze (32°F) | May 8 | Apr 21 | Apr 5 |
| Hard (28°F) | Apr 24 | Apr 3 | Mar 12 |
| Severe (24°F) | Apr 3 | Mar 10 | Feb 20 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 20 | May 15 | May 11 | May 8 | May 5 | May 3 | Apr 30 | Apr 26 | Apr 21 |
| 32°F | May 8 | May 2 | Apr 28 | Apr 24 | Apr 21 | Apr 16 | Apr 13 | Apr 10 | Apr 5 |
| 28°F | Apr 24 | Apr 16 | Apr 10 | Apr 6 | Apr 3 | Mar 30 | Mar 25 | Mar 18 | Mar 12 |
| 24°F | Apr 3 | Mar 25 | Mar 18 | Mar 14 | Mar 10 | Mar 7 | Mar 3 | Feb 27 | Feb 20 |
| 20°F | Mar 10 | Mar 6 | Mar 2 | Feb 26 | Feb 21 | Feb 17 | Feb 11 | Feb 4 | Jan 30 |
| 16°F | Feb 28 | Feb 19 | Feb 13 | Feb 7 | Feb 1 | Jan 27 | Jan 21 | Jan 14 | Jan 5 |
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) | Oct 7 | Oct 18 | Oct 28 |
| Freeze (32°F) | Oct 16 | Oct 27 | Nov 7 |
| Hard (28°F) | Oct 24 | Nov 5 | Nov 19 |
| Severe (24°F) | Nov 2 | Nov 16 | Dec 1 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 7 | Oct 12 | Oct 14 | Oct 16 | Oct 18 | Oct 20 | Oct 22 | Oct 24 | Oct 28 |
| 32°F | Oct 16 | Oct 19 | Oct 22 | Oct 24 | Oct 27 | Oct 29 | Nov 1 | Nov 3 | Nov 7 |
| 28°F | Oct 24 | Oct 29 | Oct 31 | Nov 3 | Nov 5 | Nov 8 | Nov 12 | Nov 15 | Nov 19 |
| 24°F | Nov 2 | Nov 6 | Nov 10 | Nov 13 | Nov 16 | Nov 18 | Nov 22 | Nov 26 | Dec 1 |
| 20°F | Nov 11 | Nov 16 | Nov 20 | Nov 24 | Nov 28 | Dec 1 | Dec 6 | Dec 11 | Dec 17 |
| 16°F | Nov 20 | Nov 27 | Dec 2 | Dec 8 | Dec 14 | Dec 19 | Dec 24 | Dec 31 | Jan 7 |
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: Paradise, Az, about 8.7 miles away@if(!empty($station['elevation_ft'])), at 5,460 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 San Simon, AZ?
On average, the last spring frost (32°F) around San Simon, AZ is about Apr 21. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 5.
When is the first frost in the fall?
The first fall frost around San Simon, AZ typically arrives about Oct 27. 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 Apr 21 on average, or Apr 5 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 188 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 85632 Planting calendar → Arizona frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026