Frost dates for 95418Calpella, CA
The average last spring frost in Calpella is March 19 and the average first fall frost is November 20, giving a typical growing season of about 245 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 19
- Average first fall frost
- Nov 20
- Growing season
- 245 days
Safer after Apr 15 (1-in-10 risk)
Possible by Nov 2 (1-in-10 risk)
First frost typically in 17 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) | Mar 31 · Apr 17 · May 9 | Oct 18 · Nov 2 · Nov 19 | 198 days | 100% |
| Frost / freeze (32°F) | Feb 13 · Mar 19 · Apr 15 | Nov 2 · Nov 20 · Dec 9 | 245 days | 100% |
| Hard freeze (28°F) | Dec 25 · Feb 6 · Mar 13 | Nov 17 · Dec 5 · Jan 6 | 309 days | 94% |
Planting calendar for Calpella
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 | Feb 16 – Apr 24 |
| Tomatoes | Transplant outdoors | Apr 4 – Jul 31 |
| Peppers | Start seeds indoors | Feb 16 – Mar 19 |
| Peppers | Transplant outdoors | Apr 18 – May 19 |
| Eggplant | Start seeds indoors | Mar 5 – Apr 3 |
| Eggplant | Transplant outdoors | Apr 18 – May 19 |
| Cucumbers | Sow outdoors | Apr 18 – Aug 10 |
| Summer squash | Sow outdoors | Apr 4 – May 19 |
| Winter squash & pumpkins | Sow outdoors | Apr 18 – May 19 |
| Snap beans | Sow outdoors | Apr 4 – Sep 2 |
| Sweet corn | Sow outdoors | Apr 4 – Jul 31 |
| Watermelon & cantaloupe | Sow outdoors | Apr 18 – May 19 |
| Okra | Sow outdoors | Apr 11 – May 4 |
| Peas | Sow outdoors (spring) | Feb 16 – Apr 3 |
| Potatoes | Plant outdoors (spring) | Feb 16 – Apr 18 |
| Onions | Start seeds indoors (spring) | Jan 5 – Feb 1 |
| Onions | Transplant outdoors (spring) | Mar 5 – Apr 3 |
| Broccoli | Start seeds indoors (spring) | Jan 29 – Mar 4 |
| Broccoli | Transplant outdoors (spring) | Mar 5 – Apr 3 |
| Broccoli | Start seeds indoors (fall) | Jul 21 – Jul 31 |
| Broccoli | Transplant outdoors (fall) | Aug 20 – Aug 31 |
| Cabbage | Start seeds indoors (spring) | Jan 19 – Feb 16 |
| Cabbage | Transplant outdoors (spring) | Feb 16 – Mar 19 |
| Cabbage | Start seeds indoors (fall) | Jul 11 – Aug 10 |
| Cabbage | Transplant outdoors (fall) | Aug 10 – Sep 10 |
| Leaf lettuce | Sow outdoors (spring) | Feb 16 – May 4 |
| Leaf lettuce | Sow outdoors (fall) | Aug 10 – Sep 26 |
| Spinach | Sow outdoors (spring) | Feb 9 – Mar 25 |
| Spinach | Sow outdoors (fall) | Aug 27 – Oct 1 |
| Radishes | Sow outdoors (spring) | Feb 16 – Apr 8 |
| Radishes | Sow outdoors (fall) | Aug 10 – Oct 11 |
| Kale | Sow outdoors (spring) | Mar 5 – Mar 25 |
| Kale | Sow outdoors (fall) | Aug 3 – Sep 10 |
| Carrots | Sow outdoors (spring) | Mar 19 – May 4 |
| Carrots | Sow outdoors (fall) | Jul 11 – Aug 26 |
| Garlic | Plant outdoors (fall) | Nov 10 – Dec 11 |
Where these dates come from
ZIP code 95418 is matched to the NOAA station Ukiah, CA, 8.3 km away, at 636 ft elevation (237 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Ukiah, CA (used) | 636 ft | Mar 19 | Nov 20 |
| Ukiah Muni Ap, CA | 601 ft | Mar 5 | Nov 21 |
| Potter Valley Powerhouse, CA | 1,018 ft | Apr 8 | Nov 6 |
| Willits 1 Ne, CA | 1,353 ft | May 5 | Oct 9 |
Frost dates near Calpella
- Redwood Valley, CA 95470 · last Mar 19, first Nov 20
- Ukiah, CA 95482 · last Mar 19, first Nov 20
- Talmage, CA 95481 · last Mar 5, first Nov 21
- Witter Springs, CA 95493 · last Apr 8, first Nov 6
- Potter Valley, CA 95469 · last Apr 8, first Nov 6
- Philo, CA 95466 · last Mar 5, first Nov 21
- Upper Lake, CA 95485 · last Apr 8, first Nov 6
- Boonville, CA 95415 · last Mar 5, first Nov 21
Frequently asked questions
- When is the last frost in Calpella, CA?
- For ZIP code 95418, the average last spring frost (32°F) is March 19, based on NOAA 1991-2020 climate normals for the Ukiah, CA weather station. There is a 1-in-10 chance of a frost after April 15.
- When is the first frost in Calpella, CA?
- The average first fall frost (32°F) is November 20. There is a 1-in-10 chance of frost by November 2, so tender plants are at risk from that point on.
- How long is the growing season in 95418?
- 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.