Frost dates for 57706Ellsworth Afb, SD
The average last spring frost in Ellsworth Afb is May 12 and the average first fall frost is October 1, giving a typical growing season of about 139 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 12
- Average first fall frost
- Oct 1
- Growing season
- 139 days
Safer after May 26 (1-in-10 risk)
Possible by Sep 16 (1-in-10 risk)
Last frost typically in 191 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 10 · May 22 · Jun 6 | Sep 7 · Sep 21 · Oct 3 | 121 days | 100% |
| Frost / freeze (32°F) | May 1 · May 12 · May 26 | Sep 16 · Oct 1 · Oct 14 | 139 days | 100% |
| Hard freeze (28°F) | Apr 18 · May 2 · May 14 | Sep 26 · Oct 9 · Oct 23 | 159 days | 100% |
Planting calendar for Ellsworth Afb
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 11 – Jun 17 |
| Tomatoes | Transplant outdoors | May 28 – Jun 11 |
| Peppers | Start seeds indoors | Apr 11 – May 12 |
| Peppers | Transplant outdoors | Jun 11 – Jul 12 |
| Eggplant | Start seeds indoors | Apr 28 – May 27 |
| Eggplant | Transplant outdoors | Jun 11 – Jul 12 |
| Cucumbers | Sow outdoors | Jun 11 – Jun 21 |
| Summer squash | Sow outdoors | May 28 – Jul 12 |
| Winter squash & pumpkins | Sow outdoors | Jun 11 – Jul 12 |
| Snap beans | Sow outdoors | May 28 – Jul 14 |
| Sweet corn | Sow outdoors | May 28 – Jun 11 |
| Watermelon & cantaloupe | Sow outdoors | Jun 11 – Jul 12 |
| Okra | Sow outdoors | Jun 4 – Jun 27 |
| Peas | Sow outdoors (spring) | Apr 11 – May 27 |
| Potatoes | Plant outdoors (spring) | Apr 11 – Jun 11 |
| Onions | Start seeds indoors (spring) | Feb 28 – Mar 27 |
| Onions | Transplant outdoors (spring) | Apr 28 – May 27 |
| Broccoli | Start seeds indoors (spring) | Mar 24 – Apr 27 |
| Broccoli | Transplant outdoors (spring) | Apr 28 – May 27 |
| Broccoli | Start seeds indoors (fall) | Jun 1 – Jun 11 |
| Broccoli | Transplant outdoors (fall) | Jul 1 – Jul 12 |
| Cabbage | Start seeds indoors (spring) | Mar 14 – Apr 11 |
| Cabbage | Transplant outdoors (spring) | Apr 11 – May 12 |
| Cabbage | Start seeds indoors (fall) | May 22 – Jun 21 |
| Cabbage | Transplant outdoors (fall) | Jun 21 – Jul 22 |
| Leaf lettuce | Sow outdoors (spring) | Apr 11 – Jun 27 |
| Leaf lettuce | Sow outdoors (fall) | Jun 21 – Aug 7 |
| Spinach | Sow outdoors (spring) | Apr 4 – May 18 |
| Spinach | Sow outdoors (fall) | Jul 8 – Aug 12 |
| Radishes | Sow outdoors (spring) | Apr 11 – Jun 1 |
| Radishes | Sow outdoors (fall) | Jun 21 – Aug 22 |
| Kale | Sow outdoors (spring) | Apr 28 – May 18 |
| Kale | Sow outdoors (fall) | Jun 14 – Jul 22 |
| Carrots | Sow outdoors (spring) | May 12 – Jun 27 |
| Carrots | Sow outdoors (fall) | May 22 – Jul 7 |
| Garlic | Plant outdoors (fall) | Sep 21 – Oct 22 |
Where these dates come from
ZIP code 57706 is matched to the NOAA station Rapid City Rgnl Ap, SD, 11.4 km away, at 3,160 ft elevation (39 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Rapid City Rgnl Ap, SD (used) | 3,160 ft | May 12 | Oct 1 |
| Rapid City Wfo, SD | 3,379 ft | May 3 | Oct 8 |
| Rapid City 4Nw, SD | 3,479 ft | May 10 | Oct 5 |
| Hereford 12 Sw, SD | 2,810 ft | May 8 | Oct 3 |
Frost dates near Ellsworth Afb
- Box Elder, SD 57719 · last May 12, first Oct 1
- Rapid City, SD 57701 · last May 3, first Oct 8
- Black Hawk, SD 57718 · last May 20, first Sep 25
- New Underwood, SD 57761 · last May 12, first Oct 1
- Piedmont, SD 57769 · last May 10, first Oct 5
- Caputa, SD 57725 · last May 12, first Oct 1
- Sturgis, SD 57785 · last May 8, first Oct 3
- Hermosa, SD 57744 · last May 3, first Oct 8
Frequently asked questions
- When is the last frost in Ellsworth Afb, SD?
- For ZIP code 57706, the average last spring frost (32°F) is May 12, based on NOAA 1991-2020 climate normals for the Rapid City Rgnl Ap, SD weather station. There is a 1-in-10 chance of a frost after May 26.
- When is the first frost in Ellsworth Afb, SD?
- The average first fall frost (32°F) is October 1. There is a 1-in-10 chance of frost by September 16, so tender plants are at risk from that point on.
- How long is the growing season in 57706?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 139 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.