Last spring frost
Mar 20
Frost Dates for Patagonia, AZ
First fall frost
Nov 17
Growing season
239 days
Hardiness zone
8a
In an average year around Patagonia, AZ, the last spring frost (32°F) is about Mar 20 and the first fall frost is about Nov 17, giving roughly a 239-day growing season. To be safe most years, wait until Feb 24 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) | Apr 29 | Apr 13 | Mar 24 |
| Freeze (32°F) | Apr 13 | Mar 20 | Feb 24 |
| Hard (28°F) | Mar 21 | Feb 23 | Jan 25 |
| Severe (24°F) | Feb 23 | Jan 31 | Dec 28 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 29 | Apr 24 | Apr 19 | Apr 16 | Apr 13 | Apr 9 | Apr 6 | Apr 1 | Mar 24 |
| 32°F | Apr 13 | Apr 6 | Mar 31 | Mar 26 | Mar 20 | Mar 14 | Mar 9 | Mar 3 | Feb 24 |
| 28°F | Mar 21 | Mar 11 | Mar 5 | Feb 28 | Feb 23 | Feb 17 | Feb 10 | Feb 4 | Jan 25 |
| 24°F | Feb 23 | Feb 15 | Feb 9 | Feb 5 | Jan 31 | Jan 24 | Jan 16 | Jan 9 | Dec 28 |
| 20°F | Feb 10 | Feb 3 | Jan 27 | Jan 20 | Jan 13 | Jan 7 | Jan 2 | Dec 27 | Dec 19 |
| 16°F | Feb 6 | Jan 30 | Jan 24 | Jan 19 | Jan 10 | Jan 7 | Jan 4 | Dec 30 | Dec 24 |
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 20 | Nov 5 | Nov 20 |
| Freeze (32°F) | Oct 30 | Nov 17 | Dec 3 |
| Hard (28°F) | Nov 11 | Nov 30 | Dec 17 |
| Severe (24°F) | Nov 24 | Dec 17 | Jan 18 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 20 | Oct 26 | Oct 29 | Nov 1 | Nov 5 | Nov 8 | Nov 11 | Nov 15 | Nov 20 |
| 32°F | Oct 30 | Nov 4 | Nov 9 | Nov 13 | Nov 17 | Nov 20 | Nov 24 | Nov 29 | Dec 3 |
| 28°F | Nov 11 | Nov 17 | Nov 22 | Nov 25 | Nov 30 | Dec 3 | Dec 6 | Dec 11 | Dec 17 |
| 24°F | Nov 24 | Dec 1 | Dec 8 | Dec 13 | Dec 17 | Dec 22 | Dec 27 | Jan 3 | Jan 18 |
| 20°F | Dec 11 | Dec 18 | Dec 26 | Dec 30 | Jan 3 | Jan 9 | Jan 17 | Jan 26 | Feb 4 |
| 16°F | Dec 24 | Dec 30 | Jan 3 | Jan 5 | Jan 9 | Jan 17 | Jan 23 | Jan 30 | Feb 5 |
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: Nogales Intl Ap, Az, about 10 miles away@if(!empty($station['elevation_ft'])), at 3,932 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 Patagonia, AZ?
On average, the last spring frost (32°F) around Patagonia, AZ is about Mar 20. In cooler years it can run later, so for a safer bet many gardeners wait until Feb 24.
When is the first frost in the fall?
The first fall frost around Patagonia, AZ typically arrives about Nov 17. 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 Mar 20 on average, or Feb 24 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 239 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 85624 Planting calendar → Arizona frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026