Frost dates for 96091Trinity Center, CA
The average last spring frost in Trinity Center is May 15 and the average first fall frost is October 6, giving a typical growing season of about 143 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 15
- Average first fall frost
- Oct 6
- Growing season
- 143 days
Safer after Jun 5 (1-in-10 risk)
Possible by Sep 20 (1-in-10 risk)
Last frost typically in 200 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 19 · Jun 6 · Jun 27 | Sep 3 · Sep 19 · Oct 5 | 101 days | 100% |
| Frost / freeze (32°F) | Apr 29 · May 15 · Jun 5 | Sep 20 · Oct 6 · Oct 24 | 143 days | 100% |
| Hard freeze (28°F) | Apr 11 · Apr 29 · May 14 | Oct 6 · Oct 25 · Nov 9 | 179 days | 100% |
Planting calendar for Trinity Center
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 14 – Jun 20 |
| Tomatoes | Transplant outdoors | May 31 – Jun 16 |
| Peppers | Start seeds indoors | Apr 14 – May 15 |
| Peppers | Transplant outdoors | Jun 14 – Jul 15 |
| Eggplant | Start seeds indoors | May 1 – May 30 |
| Eggplant | Transplant outdoors | Jun 14 – Jul 15 |
| Cucumbers | Sow outdoors | Jun 14 – Jun 26 |
| Summer squash | Sow outdoors | May 31 – Jul 15 |
| Winter squash & pumpkins | Sow outdoors | Jun 14 – Jul 15 |
| Snap beans | Sow outdoors | May 31 – Jul 19 |
| Sweet corn | Sow outdoors | May 31 – Jun 16 |
| Watermelon & cantaloupe | Sow outdoors | Jun 14 – Jul 15 |
| Okra | Sow outdoors | Jun 7 – Jun 30 |
| Peas | Sow outdoors (spring) | Apr 14 – May 30 |
| Potatoes | Plant outdoors (spring) | Apr 14 – Jun 14 |
| Onions | Start seeds indoors (spring) | Mar 3 – Mar 30 |
| Onions | Transplant outdoors (spring) | May 1 – May 30 |
| Broccoli | Start seeds indoors (spring) | Mar 27 – Apr 30 |
| Broccoli | Transplant outdoors (spring) | May 1 – May 30 |
| Broccoli | Start seeds indoors (fall) | Jun 6 – Jun 16 |
| Broccoli | Transplant outdoors (fall) | Jul 6 – Jul 17 |
| Cabbage | Start seeds indoors (spring) | Mar 17 – Apr 14 |
| Cabbage | Transplant outdoors (spring) | Apr 14 – May 15 |
| Cabbage | Start seeds indoors (fall) | May 27 – Jun 26 |
| Cabbage | Transplant outdoors (fall) | Jun 26 – Jul 27 |
| Leaf lettuce | Sow outdoors (spring) | Apr 14 – Jun 30 |
| Leaf lettuce | Sow outdoors (fall) | Jun 26 – Aug 12 |
| Spinach | Sow outdoors (spring) | Apr 7 – May 21 |
| Spinach | Sow outdoors (fall) | Jul 13 – Aug 17 |
| Radishes | Sow outdoors (spring) | Apr 14 – Jun 4 |
| Radishes | Sow outdoors (fall) | Jun 26 – Aug 27 |
| Kale | Sow outdoors (spring) | May 1 – May 21 |
| Kale | Sow outdoors (fall) | Jun 19 – Jul 27 |
| Carrots | Sow outdoors (spring) | May 15 – Jun 30 |
| Carrots | Sow outdoors (fall) | May 27 – Jul 12 |
| Garlic | Plant outdoors (fall) | Sep 26 – Oct 27 |
Where these dates come from
ZIP code 96091 is matched to the NOAA station Mt Shasta, CA, 44.6 km away, at 3,613 ft elevation (39 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Mt Shasta, CA (used) | 3,613 ft | May 15 | Oct 6 |
| Callahan, CA | 3,085 ft | May 20 | Oct 5 |
| Cecilville, CA | 2,310 ft | Apr 27 | Oct 21 |
| Trinity Rvr Hatchery, CA | 1,861 ft | Apr 23 | Oct 22 |
Frost dates near Trinity Center
- Lakehead, CA 96051 · last Apr 23, first Oct 27
- Castella, CA 96017 · last Apr 23, first Oct 27
- Callahan, CA 96014 · last May 20, first Oct 5
- Lewiston, CA 96052 · last May 3, first Oct 11
- French Gulch, CA 96033 · last Apr 23, first Oct 22
- Weaverville, CA 96093 · last May 3, first Oct 11
- Dunsmuir, CA 96025 · last Apr 23, first Oct 27
- Mount Shasta, CA 96067 · last May 6, first Oct 12
Frequently asked questions
- When is the last frost in Trinity Center, CA?
- For ZIP code 96091, the average last spring frost (32°F) is May 15, based on NOAA 1991-2020 climate normals for the Mt Shasta, CA weather station. There is a 1-in-10 chance of a frost after June 5.
- When is the first frost in Trinity Center, CA?
- The average first fall frost (32°F) is October 6. There is a 1-in-10 chance of frost by September 20, so tender plants are at risk from that point on.
- How long is the growing season in 96091?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 143 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.