Last spring frost
May 3
Frost Dates for Junction City, CA
First fall frost
Oct 11
Growing season
159 days
Hardiness zone
8b
In an average year around Junction City, CA, the last spring frost (32°F) is about May 3 and the first fall frost is about Oct 11, giving roughly a 159-day growing season. To be safe most years, wait until Apr 16 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 18 | May 30 | May 7 |
| Freeze (32°F) | May 27 | May 3 | Apr 16 |
| Hard (28°F) | Apr 30 | Apr 11 | Mar 20 |
| Severe (24°F) | Apr 12 | Mar 15 | Feb 1 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 18 | Jun 11 | Jun 6 | Jun 2 | May 30 | May 25 | May 20 | May 14 | May 7 |
| 32°F | May 27 | May 16 | May 11 | May 6 | May 3 | Apr 30 | Apr 27 | Apr 21 | Apr 16 |
| 28°F | Apr 30 | Apr 26 | Apr 20 | Apr 16 | Apr 11 | Apr 7 | Apr 3 | Mar 28 | Mar 20 |
| 24°F | Apr 12 | Apr 4 | Mar 29 | Mar 22 | Mar 15 | Mar 8 | Mar 1 | Feb 19 | Feb 1 |
| 20°F | Mar 7 | Feb 27 | Feb 18 | Feb 9 | Jan 29 | Jan 13 | Jan 3 | Dec 27 | Dec 11 |
| 16°F | Feb 14 | Jan 31 | Jan 14 | Jan 3 | Dec 31 | Dec 22 | Dec 13 | Dec 6 | Nov 28 |
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 11 | Sep 28 | Oct 14 |
| Freeze (32°F) | Sep 28 | Oct 11 | Nov 1 |
| Hard (28°F) | Oct 8 | Oct 29 | Nov 23 |
| Severe (24°F) | Oct 20 | Nov 18 | Dec 22 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 11 | Sep 16 | Sep 21 | Sep 25 | Sep 28 | Oct 1 | Oct 3 | Oct 7 | Oct 14 |
| 32°F | Sep 28 | Oct 1 | Oct 5 | Oct 8 | Oct 11 | Oct 15 | Oct 21 | Oct 26 | Nov 1 |
| 28°F | Oct 8 | Oct 14 | Oct 19 | Oct 25 | Oct 29 | Nov 1 | Nov 7 | Nov 14 | Nov 23 |
| 24°F | Oct 20 | Oct 29 | Nov 4 | Nov 10 | Nov 18 | Nov 24 | Dec 1 | Dec 9 | Dec 22 |
| 20°F | Nov 4 | Nov 15 | Nov 25 | Dec 1 | Dec 9 | Dec 16 | Dec 25 | Jan 4 | Jan 29 |
| 16°F | Nov 16 | Nov 30 | Dec 4 | Dec 11 | Dec 19 | Dec 26 | Jan 1 | Jan 12 | Feb 3 |
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: Weaverville, Ca, about 7.8 miles away@if(!empty($station['elevation_ft'])), at 2,058 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 Junction City, CA?
On average, the last spring frost (32°F) around Junction City, CA is about May 3. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 16.
When is the first frost in the fall?
The first fall frost around Junction City, CA typically arrives about Oct 11. 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 May 3 on average, or Apr 16 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 159 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 96048 Planting calendar → California frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026