Last spring frost
Feb 25
Frost Dates for Morongo Valley, CA
First fall frost
Dec 15
Growing season
297 days
Hardiness zone
9a
In an average year around Morongo Valley, CA, the last spring frost (32°F) is about Feb 25 and the first fall frost is about Dec 15, giving roughly a 297-day growing season. To be safe most years, wait until Jan 7 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 | Mar 31 | Feb 20 |
| Freeze (32°F) | Apr 3 | Feb 25 | Jan 7 |
| Hard (28°F) | Feb 28 | Jan 25 | Dec 20 |
| Severe (24°F) | Jan 31 | Jan 14 | Jan 3 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 29 | Apr 19 | Apr 12 | Apr 7 | Mar 31 | Mar 24 | Mar 16 | Mar 7 | Feb 20 |
| 32°F | Apr 3 | Mar 22 | Mar 11 | Mar 2 | Feb 25 | Feb 14 | Feb 3 | Jan 21 | Jan 7 |
| 28°F | Feb 28 | Feb 22 | Feb 14 | Feb 1 | Jan 25 | Jan 16 | Jan 8 | Jan 1 | Dec 20 |
| 24°F | Jan 31 | Jan 26 | Jan 22 | Jan 17 | Jan 14 | Jan 12 | Jan 10 | Jan 6 | Jan 3 |
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) | Nov 7 | Dec 1 | Dec 16 |
| Freeze (32°F) | Nov 23 | Dec 15 | Jan 16 |
| Hard (28°F) | Dec 8 | Jan 6 | Feb 14 |
| Severe (24°F) | Jan 2 | Jan 13 | Jan 30 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 7 | Nov 16 | Nov 22 | Nov 28 | Dec 1 | Dec 5 | Dec 9 | Dec 12 | Dec 16 |
| 32°F | Nov 23 | Dec 1 | Dec 7 | Dec 11 | Dec 15 | Dec 19 | Dec 24 | Jan 1 | Jan 16 |
| 28°F | Dec 8 | Dec 17 | Dec 25 | Dec 30 | Jan 6 | Jan 12 | Jan 21 | Jan 30 | Feb 14 |
| 24°F | Jan 2 | Jan 5 | Jan 9 | Jan 11 | Jan 13 | Jan 15 | Jan 20 | Jan 24 | Jan 30 |
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: Morongo Valley N, Ca, about 5.2 miles away@if(!empty($station['elevation_ft'])), at 3,145 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 Morongo Valley, CA?
On average, the last spring frost (32°F) around Morongo Valley, CA is about Feb 25. In cooler years it can run later, so for a safer bet many gardeners wait until Jan 7.
When is the first frost in the fall?
The first fall frost around Morongo Valley, CA typically arrives about Dec 15. 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 25 on average, or Jan 7 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 297 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 92268 Planting calendar → California frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026