Last spring frost
Mar 11
Frost Dates for San Carlos, AZ
First fall frost
Nov 21
Growing season
253 days
Hardiness zone
9a
In an average year around San Carlos, AZ, the last spring frost (32°F) is about Mar 11 and the first fall frost is about Nov 21, giving roughly a 253-day growing season. To be safe most years, wait until Feb 19 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 18 | Mar 30 | Mar 12 |
| Freeze (32°F) | Mar 29 | Mar 11 | Feb 19 |
| Hard (28°F) | Mar 11 | Feb 21 | Jan 23 |
| Severe (24°F) | Feb 24 | Jan 24 | Dec 28 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 18 | Apr 10 | Apr 6 | Apr 2 | Mar 30 | Mar 25 | Mar 22 | Mar 18 | Mar 12 |
| 32°F | Mar 29 | Mar 22 | Mar 18 | Mar 14 | Mar 11 | Mar 7 | Mar 4 | Feb 28 | Feb 19 |
| 28°F | Mar 11 | Mar 6 | Mar 2 | Feb 26 | Feb 21 | Feb 16 | Feb 9 | Feb 2 | Jan 23 |
| 24°F | Feb 24 | Feb 16 | Feb 7 | Feb 1 | Jan 24 | Jan 18 | Jan 11 | Jan 6 | Dec 28 |
| 20°F | Feb 4 | Jan 23 | Jan 15 | Jan 9 | Jan 5 | Jan 1 | Dec 30 | Dec 23 | Dec 15 |
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 25 | Nov 12 | Nov 25 |
| Freeze (32°F) | Nov 6 | Nov 21 | Dec 6 |
| Hard (28°F) | Nov 17 | Dec 3 | Dec 19 |
| Severe (24°F) | Nov 28 | Dec 16 | Jan 9 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 25 | Nov 1 | Nov 4 | Nov 9 | Nov 12 | Nov 14 | Nov 17 | Nov 20 | Nov 25 |
| 32°F | Nov 6 | Nov 12 | Nov 15 | Nov 18 | Nov 21 | Nov 24 | Nov 27 | Dec 1 | Dec 6 |
| 28°F | Nov 17 | Nov 23 | Nov 26 | Nov 30 | Dec 3 | Dec 6 | Dec 9 | Dec 13 | Dec 19 |
| 24°F | Nov 28 | Dec 4 | Dec 8 | Dec 12 | Dec 16 | Dec 20 | Dec 25 | Dec 30 | Jan 9 |
| 20°F | Dec 10 | Dec 15 | Dec 21 | Dec 26 | Dec 29 | Jan 1 | Jan 5 | Jan 11 | Jan 21 |
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: Globe #3, Az, about 19.5 miles away@if(!empty($station['elevation_ft'])), at 3,660 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 Carlos, AZ?
On average, the last spring frost (32°F) around San Carlos, AZ is about Mar 11. In cooler years it can run later, so for a safer bet many gardeners wait until Feb 19.
When is the first frost in the fall?
The first fall frost around San Carlos, AZ typically arrives about Nov 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 Mar 11 on average, or Feb 19 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 253 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 85550 Planting calendar → Arizona frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026