Frost dates for 57718Black Hawk, SD
The average last spring frost in Black Hawk is May 20 and the average first fall frost is September 25, giving a typical growing season of about 126 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 20
- Average first fall frost
- Sep 25
- Growing season
- 126 days
Safer after Jun 3 (1-in-10 risk)
Possible by Sep 11 (1-in-10 risk)
Last frost typically in 199 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 2 · Jun 18 | Sep 1 · Sep 15 · Sep 27 | 104 days | 100% |
| Frost / freeze (32°F) | May 9 · May 20 · Jun 3 | Sep 11 · Sep 25 · Oct 7 | 126 days | 100% |
| Hard freeze (28°F) | Apr 25 · May 8 · May 22 | Sep 21 · Oct 4 · Oct 17 | 148 days | 100% |
Planting calendar for Black Hawk
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 19 – Jun 25 |
| Tomatoes | Transplant outdoors | Jun 5 – Jun 5 |
| Peppers | Start seeds indoors | Apr 19 – May 20 |
| Peppers | Transplant outdoors | Jun 19 – Jul 20 |
| Eggplant | Start seeds indoors | May 6 – Jun 4 |
| Eggplant | Transplant outdoors | Jun 19 – Jul 20 |
| Cucumbers | Sow outdoors | Jun 19 – Jun 15 |
| Summer squash | Sow outdoors | Jun 5 – Jul 20 |
| Winter squash & pumpkins | Sow outdoors | Jun 19 – Jul 20 |
| Snap beans | Sow outdoors | Jun 5 – Jul 8 |
| Sweet corn | Sow outdoors | Jun 5 – Jun 5 |
| Watermelon & cantaloupe | Sow outdoors | Jun 19 – Jul 20 |
| Okra | Sow outdoors | Jun 12 – Jul 5 |
| Peas | Sow outdoors (spring) | Apr 19 – Jun 4 |
| Potatoes | Plant outdoors (spring) | Apr 19 – Jun 19 |
| Onions | Start seeds indoors (spring) | Mar 8 – Apr 4 |
| Onions | Transplant outdoors (spring) | May 6 – Jun 4 |
| Broccoli | Start seeds indoors (spring) | Apr 1 – May 5 |
| Broccoli | Transplant outdoors (spring) | May 6 – Jun 4 |
| Broccoli | Start seeds indoors (fall) | May 26 – Jun 5 |
| Broccoli | Transplant outdoors (fall) | Jun 25 – Jul 6 |
| Cabbage | Start seeds indoors (spring) | Mar 22 – Apr 19 |
| Cabbage | Transplant outdoors (spring) | Apr 19 – May 20 |
| Cabbage | Start seeds indoors (fall) | May 16 – Jun 15 |
| Cabbage | Transplant outdoors (fall) | Jun 15 – Jul 16 |
| Leaf lettuce | Sow outdoors (spring) | Apr 19 – Jul 5 |
| Leaf lettuce | Sow outdoors (fall) | Jun 15 – Aug 1 |
| Spinach | Sow outdoors (spring) | Apr 12 – May 26 |
| Spinach | Sow outdoors (fall) | Jul 2 – Aug 6 |
| Radishes | Sow outdoors (spring) | Apr 19 – Jun 9 |
| Radishes | Sow outdoors (fall) | Jun 15 – Aug 16 |
| Kale | Sow outdoors (spring) | May 6 – May 26 |
| Kale | Sow outdoors (fall) | Jun 8 – Jul 16 |
| Carrots | Sow outdoors (spring) | May 20 – Jul 5 |
| Carrots | Sow outdoors (fall) | May 16 – Jul 1 |
| Garlic | Plant outdoors (fall) | Sep 15 – Oct 16 |
Where these dates come from
ZIP code 57718 is matched to the NOAA station Johnson Siding, SD, 10.1 km away, at 4,184 ft elevation (273 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Johnson Siding, SD (used) | 4,184 ft | May 20 | Sep 25 |
| Rapid City 4Nw, SD | 3,479 ft | May 10 | Oct 5 |
| Rapid City Wfo, SD | 3,379 ft | May 3 | Oct 8 |
| Pactola Dam, SD | 4,720 ft | May 28 | Sep 18 |
Frost dates near Black Hawk
- Rapid City, SD 57709 · last May 20, first Sep 25
- Piedmont, SD 57769 · last May 10, first Oct 5
- Nemo, SD 57759 · last May 28, first Sep 18
- Ellsworth Afb, SD 57706 · last May 12, first Oct 1
- Box Elder, SD 57719 · last May 12, first Oct 1
- Sturgis, SD 57785 · last May 8, first Oct 3
- Keystone, SD 57751 · last May 28, first Sep 18
- Fort Meade, SD 57741 · last May 8, first Oct 3
Frequently asked questions
- When is the last frost in Black Hawk, SD?
- For ZIP code 57718, the average last spring frost (32°F) is May 20, based on NOAA 1991-2020 climate normals for the Johnson Siding, SD weather station. There is a 1-in-10 chance of a frost after June 3.
- When is the first frost in Black Hawk, SD?
- The average first fall frost (32°F) is September 25. There is a 1-in-10 chance of frost by September 11, so tender plants are at risk from that point on.
- How long is the growing season in 57718?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 126 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.