Frost dates for Pactola Dam, SD
At Pactola Dam, the median last spring frost (32°F) is May 28 and the median first fall frost is Sep 18, for a typical growing season of 112 days. For a 90% chance that the last frost has passed, wait until Jun 11. Nearby ZIP codes are in USDA hardiness zones 4b to 5b.
- May 28Last spring frost (median)50% chance of 32°F after this date
- Jun 11Safer planting date10% chance of 32°F after this date
- Sep 18First fall frost (median)50% chance of 32°F by this date
- 112 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | May 28 | Jun 13 | Jul 4 |
| 32°F | May 16 | May 28 | Jun 11 |
| 28°F | May 4 | May 15 | May 28 |
| 24°F | Apr 18 | May 2 | May 15 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Aug 24 | Sep 7 | Sep 20 |
| 32°F | Sep 4 | Sep 18 | Oct 1 |
| 28°F | Sep 14 | Sep 29 | Oct 12 |
| 24°F | Sep 22 | Oct 8 | Oct 24 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 60 days | 85 days | 106 days |
| 32°F | 91 days | 112 days | 129 days |
| 28°F | 118 days | 136 days | 153 days |
| 24°F | 138 days | 159 days | 177 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
Closest ZIP codes (each is closer to another station)
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 57702 | 5a | -20 to -15°F | 6 km |
| 57718 | 5a | -20 to -15°F | 15 km |
| 57759 | 5a | -20 to -15°F | 19 km |
| 57751 | 5a | -20 to -15°F | 22 km |
| 57701 | 5b | -15 to -10°F | 23 km |
| 57745 | 4b | -25 to -20°F | 25 km |
| 57769 | 5a | -20 to -15°F | 26 km |
| 57706 | 5b | -15 to -10°F | 32 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00396427, at 44.0622, -103.4819, elevation 1439 m (4,720 ft).
- Data quality: Standard (24+ years of data), 27 years of freeze data.
- Average days per year at or below 32°F: 212.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Johnson Siding (5 km)
- Hill City (15 km)
- Rapid City 4nw (17 km)
- Mount Rushmore Nmem (21 km)
- Rapid City WFO (22 km)
- Rochford 2 WNW (23 km)
- Custer (34 km)
- Rapid City Regional Airport (34 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.