Frost dates for 95925Challenge, CA
The average last spring frost in Challenge is May 4 and the average first fall frost is October 30, giving a typical growing season of about 174 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 4
- Average first fall frost
- Oct 30
- Growing season
- 174 days
Safer after May 31 (1-in-10 risk)
Possible by Oct 7 (1-in-10 risk)
Last frost typically in 182 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 6 · May 29 · Jun 14 | Sep 22 · Oct 9 · Oct 28 | 136 days | 100% |
| Frost / freeze (32°F) | Apr 18 · May 4 · May 31 | Oct 7 · Oct 30 · Nov 14 | 174 days | 100% |
| Hard freeze (28°F) | Mar 23 · Apr 15 · May 8 | Oct 28 · Nov 16 · Dec 3 | 212 days | 100% |
Planting calendar for Challenge
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 | Apr 3 – Jun 9 |
| Tomatoes | Transplant outdoors | May 20 – Jul 10 |
| Peppers | Start seeds indoors | Apr 3 – May 4 |
| Peppers | Transplant outdoors | Jun 3 – Jul 4 |
| Eggplant | Start seeds indoors | Apr 20 – May 19 |
| Eggplant | Transplant outdoors | Jun 3 – Jul 4 |
| Cucumbers | Sow outdoors | Jun 3 – Jul 20 |
| Summer squash | Sow outdoors | May 20 – Jul 4 |
| Winter squash & pumpkins | Sow outdoors | Jun 3 – Jul 4 |
| Snap beans | Sow outdoors | May 20 – Aug 12 |
| Sweet corn | Sow outdoors | May 20 – Jul 10 |
| Watermelon & cantaloupe | Sow outdoors | Jun 3 – Jul 4 |
| Okra | Sow outdoors | May 27 – Jun 19 |
| Peas | Sow outdoors (spring) | Apr 3 – May 19 |
| Potatoes | Plant outdoors (spring) | Apr 3 – Jun 3 |
| Onions | Start seeds indoors (spring) | Feb 20 – Mar 19 |
| Onions | Transplant outdoors (spring) | Apr 20 – May 19 |
| Broccoli | Start seeds indoors (spring) | Mar 16 – Apr 19 |
| Broccoli | Transplant outdoors (spring) | Apr 20 – May 19 |
| Broccoli | Start seeds indoors (fall) | Jun 30 – Jul 10 |
| Broccoli | Transplant outdoors (fall) | Jul 30 – Aug 10 |
| Cabbage | Start seeds indoors (spring) | Mar 6 – Apr 3 |
| Cabbage | Transplant outdoors (spring) | Apr 3 – May 4 |
| Cabbage | Start seeds indoors (fall) | Jun 20 – Jul 20 |
| Cabbage | Transplant outdoors (fall) | Jul 20 – Aug 20 |
| Leaf lettuce | Sow outdoors (spring) | Apr 3 – Jun 19 |
| Leaf lettuce | Sow outdoors (fall) | Jul 20 – Sep 5 |
| Spinach | Sow outdoors (spring) | Mar 27 – May 10 |
| Spinach | Sow outdoors (fall) | Aug 6 – Sep 10 |
| Radishes | Sow outdoors (spring) | Apr 3 – May 24 |
| Radishes | Sow outdoors (fall) | Jul 20 – Sep 20 |
| Kale | Sow outdoors (spring) | Apr 20 – May 10 |
| Kale | Sow outdoors (fall) | Jul 13 – Aug 20 |
| Carrots | Sow outdoors (spring) | May 4 – Jun 19 |
| Carrots | Sow outdoors (fall) | Jun 20 – Aug 5 |
| Garlic | Plant outdoors (fall) | Oct 20 – Nov 20 |
Where these dates come from
ZIP code 95925 is matched to the NOAA station Strawberry Valley, CA, 12.8 km away, at 3,808 ft elevation (649 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Strawberry Valley, CA (used) | 3,808 ft | May 4 | Oct 30 |
| Dobbins 1 S, CA | 1,640 ft | Apr 1 | Nov 17 |
| Nevada City, CA | 2,781 ft | Apr 14 | Nov 20 |
| Grass Valley #2, CA | 2,400 ft | Apr 10 | Nov 13 |
Frost dates near Challenge
- Brownsville, CA 95919 · last Apr 14, first Nov 20
- Forbestown, CA 95941 · last Apr 14, first Nov 20
- Clipper Mills, CA 95930 · last May 4, first Oct 30
- Dobbins, CA 95935 · last Apr 1, first Nov 17
- Rackerby, CA 95972 · last Apr 1, first Nov 17
- Camptonville, CA 95922 · last Apr 14, first Nov 20
- North San Juan, CA 95960 · last Apr 1, first Nov 17
- Oregon House, CA 95962 · last Apr 1, first Nov 17
Frequently asked questions
- When is the last frost in Challenge, CA?
- For ZIP code 95925, the average last spring frost (32°F) is May 4, based on NOAA 1991-2020 climate normals for the Strawberry Valley, CA weather station. There is a 1-in-10 chance of a frost after May 31.
- When is the first frost in Challenge, CA?
- The average first fall frost (32°F) is October 30. There is a 1-in-10 chance of frost by October 7, so tender plants are at risk from that point on.
- How long is the growing season in 95925?
- 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.