Last spring frost
Feb 19
Frost Dates for Fort Irwin, CA
First fall frost
Nov 26
Growing season
279 days
Hardiness zone
9a
In an average year around Fort Irwin, CA, the last spring frost (32°F) is about Feb 19 and the first fall frost is about Nov 26, giving roughly a 279-day growing season. To be safe most years, wait until Jan 23 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 6 | Mar 11 | Feb 18 |
| Freeze (32°F) | Mar 11 | Feb 19 | Jan 23 |
| Hard (28°F) | Feb 25 | Jan 28 | Dec 29 |
| Severe (24°F) | Feb 6 | Jan 7 | Dec 12 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 6 | Mar 28 | Mar 21 | Mar 16 | Mar 11 | Mar 7 | Mar 2 | Feb 26 | Feb 18 |
| 32°F | Mar 11 | Mar 4 | Feb 28 | Feb 24 | Feb 19 | Feb 13 | Feb 7 | Feb 1 | Jan 23 |
| 28°F | Feb 25 | Feb 15 | Feb 7 | Feb 2 | Jan 28 | Jan 19 | Jan 13 | Jan 5 | Dec 29 |
| 24°F | Feb 6 | Jan 29 | Jan 20 | Jan 12 | Jan 7 | Jan 1 | Dec 28 | Dec 22 | Dec 12 |
| 20°F | Jan 21 | Jan 14 | Jan 10 | Jan 8 | Jan 3 | Dec 31 | Dec 28 | Dec 21 | Dec 10 |
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 31 | Nov 16 | Nov 29 |
| Freeze (32°F) | Nov 10 | Nov 26 | Dec 11 |
| Hard (28°F) | Nov 22 | Dec 9 | Jan 1 |
| Severe (24°F) | Dec 1 | Dec 22 | Jan 21 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 31 | Nov 5 | Nov 9 | Nov 12 | Nov 16 | Nov 18 | Nov 21 | Nov 24 | Nov 29 |
| 32°F | Nov 10 | Nov 16 | Nov 20 | Nov 23 | Nov 26 | Nov 30 | Dec 3 | Dec 6 | Dec 11 |
| 28°F | Nov 22 | Nov 27 | Dec 1 | Dec 6 | Dec 9 | Dec 12 | Dec 16 | Dec 21 | Jan 1 |
| 24°F | Dec 1 | Dec 8 | Dec 12 | Dec 18 | Dec 22 | Dec 27 | Jan 1 | Jan 6 | Jan 21 |
| 20°F | Dec 9 | Dec 19 | Dec 25 | Dec 30 | Jan 1 | Jan 4 | Jan 8 | Jan 12 | Jan 20 |
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: Barstow Daggett Ap, Ca, about 33.2 miles away@if(!empty($station['elevation_ft'])), at 1,917 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 Fort Irwin, CA?
On average, the last spring frost (32°F) around Fort Irwin, CA is about Feb 19. In cooler years it can run later, so for a safer bet many gardeners wait until Jan 23.
When is the first frost in the fall?
The first fall frost around Fort Irwin, CA typically arrives about Nov 26. 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 Feb 19 on average, or Jan 23 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 279 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 92310 Planting calendar → California frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026