Frost dates for 57269Twin Brooks, SD
The average last spring frost in Twin Brooks is May 5 and the average first fall frost is October 1, giving a typical growing season of about 149 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 5
- Average first fall frost
- Oct 1
- Growing season
- 149 days
Safer after May 18 (1-in-10 risk)
Possible by Sep 21 (1-in-10 risk)
Last frost typically in 185 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 2 · May 14 · May 27 | Sep 13 · Sep 24 · Oct 4 | 133 days | 100% |
| Frost / freeze (32°F) | Apr 24 · May 5 · May 18 | Sep 21 · Oct 1 · Oct 13 | 149 days | 100% |
| Hard freeze (28°F) | Apr 14 · Apr 27 · May 7 | Sep 29 · Oct 11 · Oct 25 | 167 days | 100% |
Planting calendar for Twin Brooks
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 4 – Jun 10 |
| Tomatoes | Transplant outdoors | May 21 – Jun 11 |
| Peppers | Start seeds indoors | Apr 4 – May 5 |
| Peppers | Transplant outdoors | Jun 4 – Jul 5 |
| Eggplant | Start seeds indoors | Apr 21 – May 20 |
| Eggplant | Transplant outdoors | Jun 4 – Jul 5 |
| Cucumbers | Sow outdoors | Jun 4 – Jun 21 |
| Summer squash | Sow outdoors | May 21 – Jul 5 |
| Winter squash & pumpkins | Sow outdoors | Jun 4 – Jul 5 |
| Snap beans | Sow outdoors | May 21 – Jul 14 |
| Sweet corn | Sow outdoors | May 21 – Jun 11 |
| Watermelon & cantaloupe | Sow outdoors | Jun 4 – Jul 5 |
| Okra | Sow outdoors | May 28 – Jun 20 |
| Peas | Sow outdoors (spring) | Apr 4 – May 20 |
| Potatoes | Plant outdoors (spring) | Apr 4 – Jun 4 |
| Onions | Start seeds indoors (spring) | Feb 21 – Mar 20 |
| Onions | Transplant outdoors (spring) | Apr 21 – May 20 |
| Broccoli | Start seeds indoors (spring) | Mar 17 – Apr 20 |
| Broccoli | Transplant outdoors (spring) | Apr 21 – May 20 |
| Broccoli | Start seeds indoors (fall) | Jun 1 – Jun 11 |
| Broccoli | Transplant outdoors (fall) | Jul 1 – Jul 12 |
| Cabbage | Start seeds indoors (spring) | Mar 7 – Apr 4 |
| Cabbage | Transplant outdoors (spring) | Apr 4 – May 5 |
| Cabbage | Start seeds indoors (fall) | May 22 – Jun 21 |
| Cabbage | Transplant outdoors (fall) | Jun 21 – Jul 22 |
| Leaf lettuce | Sow outdoors (spring) | Apr 4 – Jun 20 |
| Leaf lettuce | Sow outdoors (fall) | Jun 21 – Aug 7 |
| Spinach | Sow outdoors (spring) | Mar 28 – May 11 |
| Spinach | Sow outdoors (fall) | Jul 8 – Aug 12 |
| Radishes | Sow outdoors (spring) | Apr 4 – May 25 |
| Radishes | Sow outdoors (fall) | Jun 21 – Aug 22 |
| Kale | Sow outdoors (spring) | Apr 21 – May 11 |
| Kale | Sow outdoors (fall) | Jun 14 – Jul 22 |
| Carrots | Sow outdoors (spring) | May 5 – Jun 20 |
| Carrots | Sow outdoors (fall) | May 22 – Jul 7 |
| Garlic | Plant outdoors (fall) | Sep 21 – Oct 22 |
Where these dates come from
ZIP code 57269 is matched to the NOAA station Wilmot, SD, 19.9 km away, at 1,201 ft elevation (101 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Wilmot, SD (used) | 1,201 ft | May 5 | Oct 1 |
| Milbank 4 Nw, SD | 1,145 ft | May 2 | Oct 4 |
| Milbank, SD | 1,142 ft | May 5 | Oct 2 |
| Summit 1 W, SD | 1,955 ft | May 14 | Sep 28 |
Frost dates near Twin Brooks
- Marvin, SD 57251 · last May 14, first Sep 28
- Stockholm, SD 57264 · last May 7, first Sep 30
- Milbank, SD 57252 · last May 5, first Oct 2
- South Shore, SD 57263 · last May 14, first Sep 28
- Corona, SD 57227 · last May 5, first Oct 1
- Wilmot, SD 57279 · last May 5, first Oct 1
- Big Stone City, SD 57216 · last May 5, first Oct 2
- Strandburg, SD 57265 · last May 7, first Sep 30
Frequently asked questions
- When is the last frost in Twin Brooks, SD?
- For ZIP code 57269, the average last spring frost (32°F) is May 5, based on NOAA 1991-2020 climate normals for the Wilmot, SD weather station. There is a 1-in-10 chance of a frost after May 18.
- When is the first frost in Twin Brooks, SD?
- The average first fall frost (32°F) is October 1. There is a 1-in-10 chance of frost by September 21, so tender plants are at risk from that point on.
- How long is the growing season in 57269?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 149 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.