Frost dates for 57223Castlewood, SD
The average last spring frost in Castlewood is May 10 and the average first fall frost is September 27, giving a typical growing season of about 139 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 10
- Average first fall frost
- Sep 27
- Growing season
- 139 days
Safer after May 23 (1-in-10 risk)
Possible by Sep 14 (1-in-10 risk)
Last frost typically in 195 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 8 · May 19 · Jun 1 | Sep 4 · Sep 17 · Sep 29 | 120 days | 100% |
| Frost / freeze (32°F) | Apr 29 · May 10 · May 23 | Sep 14 · Sep 27 · Oct 7 | 139 days | 100% |
| Hard freeze (28°F) | Apr 17 · May 1 · May 14 | Sep 22 · Oct 4 · Oct 18 | 156 days | 100% |
Planting calendar for Castlewood
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 9 – Jun 15 |
| Tomatoes | Transplant outdoors | May 26 – Jun 7 |
| Peppers | Start seeds indoors | Apr 9 – May 10 |
| Peppers | Transplant outdoors | Jun 9 – Jul 10 |
| Eggplant | Start seeds indoors | Apr 26 – May 25 |
| Eggplant | Transplant outdoors | Jun 9 – Jul 10 |
| Cucumbers | Sow outdoors | Jun 9 – Jun 17 |
| Summer squash | Sow outdoors | May 26 – Jul 10 |
| Winter squash & pumpkins | Sow outdoors | Jun 9 – Jul 10 |
| Snap beans | Sow outdoors | May 26 – Jul 10 |
| Sweet corn | Sow outdoors | May 26 – Jun 7 |
| Watermelon & cantaloupe | Sow outdoors | Jun 9 – Jul 10 |
| Okra | Sow outdoors | Jun 2 – Jun 25 |
| Peas | Sow outdoors (spring) | Apr 9 – May 25 |
| Potatoes | Plant outdoors (spring) | Apr 9 – Jun 9 |
| Onions | Start seeds indoors (spring) | Feb 26 – Mar 25 |
| Onions | Transplant outdoors (spring) | Apr 26 – May 25 |
| Broccoli | Start seeds indoors (spring) | Mar 22 – Apr 25 |
| Broccoli | Transplant outdoors (spring) | Apr 26 – May 25 |
| Broccoli | Start seeds indoors (fall) | May 28 – Jun 7 |
| Broccoli | Transplant outdoors (fall) | Jun 27 – Jul 8 |
| Cabbage | Start seeds indoors (spring) | Mar 12 – Apr 9 |
| Cabbage | Transplant outdoors (spring) | Apr 9 – May 10 |
| Cabbage | Start seeds indoors (fall) | May 18 – Jun 17 |
| Cabbage | Transplant outdoors (fall) | Jun 17 – Jul 18 |
| Leaf lettuce | Sow outdoors (spring) | Apr 9 – Jun 25 |
| Leaf lettuce | Sow outdoors (fall) | Jun 17 – Aug 3 |
| Spinach | Sow outdoors (spring) | Apr 2 – May 16 |
| Spinach | Sow outdoors (fall) | Jul 4 – Aug 8 |
| Radishes | Sow outdoors (spring) | Apr 9 – May 30 |
| Radishes | Sow outdoors (fall) | Jun 17 – Aug 18 |
| Kale | Sow outdoors (spring) | Apr 26 – May 16 |
| Kale | Sow outdoors (fall) | Jun 10 – Jul 18 |
| Carrots | Sow outdoors (spring) | May 10 – Jun 25 |
| Carrots | Sow outdoors (fall) | May 18 – Jul 3 |
| Garlic | Plant outdoors (fall) | Sep 17 – Oct 18 |
Where these dates come from
ZIP code 57223 is matched to the NOAA station Castlewood, SD, 0.7 km away, at 1,685 ft elevation (18 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Castlewood, SD (used) | 1,685 ft | May 10 | Sep 27 |
| Castlewood #2, SD | 1,689 ft | May 6 | Oct 1 |
| Watertown 2 S, SD | 1,772 ft | May 3 | Oct 4 |
| Watertown Rgnl Ap, SD | 1,748 ft | May 7 | Sep 30 |
Frost dates near Castlewood
- Estelline, SD 57234 · last May 10, first Sep 27
- Hayti, SD 57241 · last May 10, first Sep 27
- Kranzburg, SD 57245 · last May 7, first Sep 30
- Goodwin, SD 57238 · last May 7, first Oct 1
- Watertown, SD 57201 · last May 7, first Sep 30
- Lake Norden, SD 57248 · last May 10, first Sep 27
- Hazel, SD 57242 · last May 7, first Sep 30
- Clear Lake, SD 57226 · last May 7, first Oct 1
Frequently asked questions
- When is the last frost in Castlewood, SD?
- For ZIP code 57223, the average last spring frost (32°F) is May 10, based on NOAA 1991-2020 climate normals for the Castlewood, SD weather station. There is a 1-in-10 chance of a frost after May 23.
- When is the first frost in Castlewood, SD?
- The average first fall frost (32°F) is September 27. There is a 1-in-10 chance of frost by September 14, so tender plants are at risk from that point on.
- How long is the growing season in 57223?
- 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.