Frost dates for 91963Potrero, CA
The average last spring frost in Potrero is April 30 and the average first fall frost is October 26, giving a typical growing season of about 174 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 30
- Average first fall frost
- Oct 26
- Growing season
- 174 days
Safer after Jun 1 (1-in-10 risk)
Possible by Sep 30 (1-in-10 risk)
Last frost typically in 179 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) | May 3 · Jun 3 · Jun 29 | Sep 2 · Oct 2 · Oct 23 | 118 days | 100% |
| Frost / freeze (32°F) | Apr 9 · Apr 30 · Jun 1 | Sep 30 · Oct 26 · Nov 12 | 174 days | 100% |
| Hard freeze (28°F) | Feb 23 · Apr 2 · Apr 28 | Oct 22 · Nov 14 · Dec 5 | 226 days | 100% |
Planting calendar for Potrero
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 30 – Jun 5 |
| Tomatoes | Transplant outdoors | May 16 – Jul 6 |
| Peppers | Start seeds indoors | Mar 30 – Apr 30 |
| Peppers | Transplant outdoors | May 30 – Jun 30 |
| Eggplant | Start seeds indoors | Apr 16 – May 15 |
| Eggplant | Transplant outdoors | May 30 – Jun 30 |
| Cucumbers | Sow outdoors | May 30 – Jul 16 |
| Summer squash | Sow outdoors | May 16 – Jun 30 |
| Winter squash & pumpkins | Sow outdoors | May 30 – Jun 30 |
| Snap beans | Sow outdoors | May 16 – Aug 8 |
| Sweet corn | Sow outdoors | May 16 – Jul 6 |
| Watermelon & cantaloupe | Sow outdoors | May 30 – Jun 30 |
| Okra | Sow outdoors | May 23 – Jun 15 |
| Peas | Sow outdoors (spring) | Mar 30 – May 15 |
| Potatoes | Plant outdoors (spring) | Mar 30 – May 30 |
| Onions | Start seeds indoors (spring) | Feb 16 – Mar 15 |
| Onions | Transplant outdoors (spring) | Apr 16 – May 15 |
| Broccoli | Start seeds indoors (spring) | Mar 12 – Apr 15 |
| Broccoli | Transplant outdoors (spring) | Apr 16 – May 15 |
| Broccoli | Start seeds indoors (fall) | Jun 26 – Jul 6 |
| Broccoli | Transplant outdoors (fall) | Jul 26 – Aug 6 |
| Cabbage | Start seeds indoors (spring) | Mar 2 – Mar 30 |
| Cabbage | Transplant outdoors (spring) | Mar 30 – Apr 30 |
| Cabbage | Start seeds indoors (fall) | Jun 16 – Jul 16 |
| Cabbage | Transplant outdoors (fall) | Jul 16 – Aug 16 |
| Leaf lettuce | Sow outdoors (spring) | Mar 30 – Jun 15 |
| Leaf lettuce | Sow outdoors (fall) | Jul 16 – Sep 1 |
| Spinach | Sow outdoors (spring) | Mar 23 – May 6 |
| Spinach | Sow outdoors (fall) | Aug 2 – Sep 6 |
| Radishes | Sow outdoors (spring) | Mar 30 – May 20 |
| Radishes | Sow outdoors (fall) | Jul 16 – Sep 16 |
| Kale | Sow outdoors (spring) | Apr 16 – May 6 |
| Kale | Sow outdoors (fall) | Jul 9 – Aug 16 |
| Carrots | Sow outdoors (spring) | Apr 30 – Jun 15 |
| Carrots | Sow outdoors (fall) | Jun 16 – Aug 1 |
| Garlic | Plant outdoors (fall) | Oct 16 – Nov 16 |
Where these dates come from
ZIP code 91963 is matched to the NOAA station Campo, CA, 12.5 km away, at 2,630 ft elevation (294 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Campo, CA (used) | 2,630 ft | Apr 30 | Oct 26 |
| Campo Asos, CA | 2,641 ft | Apr 29 | Nov 1 |
| Alpine, CA | 1,695 ft | Feb 12 | Dec 24 |
| Mt Laguna #3, CA | 5,920 ft | Apr 22 | Nov 8 |
Frost dates near Potrero
- Tecate, CA 91980 · last Feb 12, first Dec 24
- Campo, CA 91906 · last Apr 29, first Nov 1
- Dulzura, CA 91917 · last Feb 12, first Dec 24
- Jamul, CA 91935 · last Feb 12, first Dec 24
- Pine Valley, CA 91962 · last Mar 27, first Dec 1
- Guatay, CA 91931 · last Mar 27, first Dec 1
- Alpine, CA 91901 · last Feb 12, first Dec 24
- Boulevard, CA 91905 · last Mar 27, first Dec 1
Frequently asked questions
- When is the last frost in Potrero, CA?
- For ZIP code 91963, the average last spring frost (32°F) is April 30, based on NOAA 1991-2020 climate normals for the Campo, CA weather station. There is a 1-in-10 chance of a frost after June 1.
- When is the first frost in Potrero, CA?
- The average first fall frost (32°F) is October 26. There is a 1-in-10 chance of frost by September 30, so tender plants are at risk from that point on.
- How long is the growing season in 91963?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 174 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.