Last spring frost
Mar 29
Frost Dates for Mammoth, AZ
First fall frost
Nov 13
Growing season
225 days
Hardiness zone
9a
In an average year around Mammoth, AZ, the last spring frost (32°F) is about Mar 29 and the first fall frost is about Nov 13, giving roughly a 225-day growing season. To be safe most years, wait until Mar 6 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 12 | Apr 16 | Mar 29 |
| Freeze (32°F) | Apr 29 | Mar 29 | Mar 6 |
| Hard (28°F) | Apr 6 | Mar 9 | Feb 12 |
| Severe (24°F) | Mar 11 | Feb 15 | Jan 14 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 12 | May 4 | Apr 27 | Apr 21 | Apr 16 | Apr 11 | Apr 7 | Apr 3 | Mar 29 |
| 32°F | Apr 29 | Apr 15 | Apr 6 | Apr 1 | Mar 29 | Mar 25 | Mar 21 | Mar 14 | Mar 6 |
| 28°F | Apr 6 | Mar 27 | Mar 20 | Mar 14 | Mar 9 | Mar 4 | Feb 28 | Feb 21 | Feb 12 |
| 24°F | Mar 11 | Mar 5 | Feb 28 | Feb 22 | Feb 15 | Feb 8 | Feb 2 | Jan 25 | Jan 14 |
| 20°F | Feb 26 | Feb 15 | Feb 7 | Jan 31 | Jan 22 | Jan 15 | Jan 8 | Jan 2 | Dec 23 |
| 16°F | Feb 13 | Feb 4 | Jan 27 | Jan 17 | Jan 12 | Jan 5 | Jan 1 | Dec 27 | Dec 13 |
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 18 | Nov 1 | Nov 16 |
| Freeze (32°F) | Oct 26 | Nov 13 | Nov 30 |
| Hard (28°F) | Nov 4 | Nov 24 | Dec 10 |
| Severe (24°F) | Nov 16 | Dec 6 | Dec 26 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 18 | Oct 23 | Oct 26 | Oct 30 | Nov 1 | Nov 4 | Nov 7 | Nov 11 | Nov 16 |
| 32°F | Oct 26 | Nov 1 | Nov 5 | Nov 9 | Nov 13 | Nov 16 | Nov 19 | Nov 23 | Nov 30 |
| 28°F | Nov 4 | Nov 11 | Nov 17 | Nov 20 | Nov 24 | Nov 27 | Dec 1 | Dec 5 | Dec 10 |
| 24°F | Nov 16 | Nov 23 | Nov 28 | Dec 2 | Dec 6 | Dec 9 | Dec 13 | Dec 19 | Dec 26 |
| 20°F | Nov 27 | Dec 3 | Dec 9 | Dec 14 | Dec 20 | Dec 27 | Jan 1 | Jan 10 | Jan 26 |
| 16°F | Dec 4 | Dec 14 | Dec 22 | Dec 30 | Jan 1 | Jan 6 | Jan 15 | Jan 24 | Feb 4 |
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: Oracle Sp, Az, about 11.7 miles away@if(!empty($station['elevation_ft'])), at 4,595 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 Mammoth, AZ?
On average, the last spring frost (32°F) around Mammoth, AZ is about Mar 29. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 6.
When is the first frost in the fall?
The first fall frost around Mammoth, AZ typically arrives about Nov 13. 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 29 on average, or Mar 6 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 225 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 85618 Planting calendar → Arizona frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026