Last spring frost
Apr 28
Frost Dates for Alleghany, CA
First fall frost
Oct 25
Growing season
178 days
Hardiness zone
8b
In an average year around Alleghany, CA, the last spring frost (32°F) is about Apr 28 and the first fall frost is about Oct 25, giving roughly a 178-day growing season. To be safe most years, wait until Apr 13 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) | Jun 11 | May 24 | May 2 |
| Freeze (32°F) | May 22 | Apr 28 | Apr 13 |
| Hard (28°F) | Apr 25 | Apr 6 | Mar 10 |
| Severe (24°F) | Mar 30 | Feb 20 | Jan 8 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 11 | Jun 5 | Jun 1 | May 28 | May 24 | May 19 | May 14 | May 9 | May 2 |
| 32°F | May 22 | May 12 | May 6 | May 1 | Apr 28 | Apr 25 | Apr 22 | Apr 18 | Apr 13 |
| 28°F | Apr 25 | Apr 19 | Apr 15 | Apr 10 | Apr 6 | Apr 1 | Mar 27 | Mar 19 | Mar 10 |
| 24°F | Mar 30 | Mar 9 | Mar 2 | Feb 26 | Feb 20 | Feb 13 | Feb 4 | Jan 23 | Jan 8 |
| 20°F | Feb 19 | Feb 8 | Jan 27 | Jan 18 | Jan 8 | Jan 2 | Dec 29 | Dec 21 | Dec 11 |
| 16°F | Jan 27 | Jan 18 | Jan 8 | Jan 1 | Dec 29 | Dec 23 | Dec 19 | Dec 14 | Dec 6 |
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) | Sep 24 | Oct 8 | Oct 22 |
| Freeze (32°F) | Oct 9 | Oct 25 | Nov 8 |
| Hard (28°F) | Oct 28 | Nov 10 | Dec 1 |
| Severe (24°F) | Nov 10 | Dec 1 | Dec 26 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 24 | Sep 28 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 18 | Oct 22 |
| 32°F | Oct 9 | Oct 15 | Oct 19 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 3 | Nov 8 |
| 28°F | Oct 28 | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 14 | Nov 19 | Nov 25 | Dec 1 |
| 24°F | Nov 10 | Nov 16 | Nov 22 | Nov 28 | Dec 1 | Dec 5 | Dec 10 | Dec 17 | Dec 26 |
| 20°F | Nov 27 | Dec 3 | Dec 9 | Dec 15 | Dec 20 | Dec 26 | Jan 1 | Jan 8 | Jan 24 |
| 16°F | Dec 3 | Dec 10 | Dec 16 | Dec 19 | Dec 24 | Dec 30 | Jan 3 | Jan 12 | Jan 25 |
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: Downieville, Ca, about 6.9 miles away@if(!empty($station['elevation_ft'])), at 2,915 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 Alleghany, CA?
On average, the last spring frost (32°F) around Alleghany, CA is about Apr 28. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 13.
When is the first frost in the fall?
The first fall frost around Alleghany, CA typically arrives about Oct 25. 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 Apr 28 on average, or Apr 13 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 178 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 95910 Planting calendar → California frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026