Frost dates for 94508Angwin, CA
The average last spring frost in Angwin is April 7 and the average first fall frost is December 5, giving a typical growing season of about 245 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 7
- Average first fall frost
- Dec 5
- Growing season
- 245 days
Safer after Apr 30 (1-in-10 risk)
Possible by Nov 14 (1-in-10 risk)
First frost typically in 35 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Apr 6 · Apr 30 · May 25 | Oct 22 · Nov 15 · Dec 5 | 195 days | 100% |
| Frost / freeze (32°F) | Feb 23 · Apr 7 · Apr 30 | Nov 14 · Dec 5 · Jan 1 | 245 days | 100% |
| Hard freeze (28°F) | Dec 23 · Feb 18 · Apr 9 | Nov 29 · Dec 30 · Mar 4 | 321 days | 83% |
Planting calendar for Angwin
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Mar 7 – May 13 |
| Tomatoes | Transplant outdoors | Apr 23 – Aug 15 |
| Peppers | Start seeds indoors | Mar 7 – Apr 7 |
| Peppers | Transplant outdoors | May 7 – Jun 7 |
| Eggplant | Start seeds indoors | Mar 24 – Apr 22 |
| Eggplant | Transplant outdoors | May 7 – Jun 7 |
| Cucumbers | Sow outdoors | May 7 – Aug 25 |
| Summer squash | Sow outdoors | Apr 23 – Jun 7 |
| Winter squash & pumpkins | Sow outdoors | May 7 – Jun 7 |
| Snap beans | Sow outdoors | Apr 23 – Sep 17 |
| Sweet corn | Sow outdoors | Apr 23 – Aug 15 |
| Watermelon & cantaloupe | Sow outdoors | May 7 – Jun 7 |
| Okra | Sow outdoors | Apr 30 – May 23 |
| Peas | Sow outdoors (spring) | Mar 7 – Apr 22 |
| Potatoes | Plant outdoors (spring) | Mar 7 – May 7 |
| Onions | Start seeds indoors (spring) | Jan 24 – Feb 20 |
| Onions | Transplant outdoors (spring) | Mar 24 – Apr 22 |
| Broccoli | Start seeds indoors (spring) | Feb 17 – Mar 23 |
| Broccoli | Transplant outdoors (spring) | Mar 24 – Apr 22 |
| Broccoli | Start seeds indoors (fall) | Aug 5 – Aug 15 |
| Broccoli | Transplant outdoors (fall) | Sep 4 – Sep 15 |
| Cabbage | Start seeds indoors (spring) | Feb 7 – Mar 7 |
| Cabbage | Transplant outdoors (spring) | Mar 7 – Apr 7 |
| Cabbage | Start seeds indoors (fall) | Jul 26 – Aug 25 |
| Cabbage | Transplant outdoors (fall) | Aug 25 – Sep 25 |
| Leaf lettuce | Sow outdoors (spring) | Mar 7 – May 23 |
| Leaf lettuce | Sow outdoors (fall) | Aug 25 – Oct 11 |
| Spinach | Sow outdoors (spring) | Feb 28 – Apr 13 |
| Spinach | Sow outdoors (fall) | Sep 11 – Oct 16 |
| Radishes | Sow outdoors (spring) | Mar 7 – Apr 27 |
| Radishes | Sow outdoors (fall) | Aug 25 – Oct 26 |
| Kale | Sow outdoors (spring) | Mar 24 – Apr 13 |
| Kale | Sow outdoors (fall) | Aug 18 – Sep 25 |
| Carrots | Sow outdoors (spring) | Apr 7 – May 23 |
| Carrots | Sow outdoors (fall) | Jul 26 – Sep 10 |
| Garlic | Plant outdoors (fall) | Nov 25 – Dec 26 |
Where these dates come from
ZIP code 94508 is matched to the NOAA station Angwin Pacific Union College, CA, 0.7 km away, at 1,715 ft elevation (88 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Angwin Pacific Union College, CA (used) | 1,715 ft | Apr 7 | Dec 5 |
| Saint Helena, CA | 225 ft | Feb 3 | Dec 4 |
| Calistoga, CA | 400 ft | Mar 2 | Nov 23 |
| Santa Rosa, CA | 166 ft | Feb 25 | Dec 1 |
Frost dates near Angwin
- Deer Park, CA 94576 · last Mar 2, first Nov 23
- Pope Valley, CA 94567 · last Mar 2, first Nov 23
- Saint Helena, CA 94574 · last Feb 3, first Dec 4
- Calistoga, CA 94515 · last Mar 2, first Nov 23
- Rutherford, CA 94573 · last Feb 3, first Dec 4
- Oakville, CA 94562 · last Feb 3, first Dec 4
- Kenwood, CA 95452 · last Feb 3, first Dec 4
- Yountville, CA 94599 · last Mar 2, first Nov 27
Frequently asked questions
- When is the last frost in Angwin, CA?
- For ZIP code 94508, the average last spring frost (32°F) is April 7, based on NOAA 1991-2020 climate normals for the Angwin Pacific Union College, CA weather station. There is a 1-in-10 chance of a frost after April 30.
- When is the first frost in Angwin, CA?
- The average first fall frost (32°F) is December 5. There is a 1-in-10 chance of frost by November 14, so tender plants are at risk from that point on.
- How long is the growing season in 94508?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 245 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.