Frost dates for Custer, SD
At Custer, the median last spring frost (32°F) is May 18 and the median first fall frost is Sep 28, for a typical growing season of 129 days. For a 90% chance that the last frost has passed, wait until Jun 1. Nearby ZIP codes are in USDA hardiness zones 4b to 5b.
- May 18Last spring frost (median)50% chance of 32°F after this date
- Jun 1Safer planting date10% chance of 32°F after this date
- Sep 28First fall frost (median)50% chance of 32°F by this date
- 129 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 16 | May 30 | Jun 15 |
| 32°F | May 5 | May 18 | Jun 1 |
| 28°F | Apr 23 | May 6 | May 22 |
| 24°F | Apr 11 | Apr 25 | May 8 |
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 | Sep 3 | Sep 17 | Oct 1 |
| 32°F | Sep 10 | Sep 28 | Oct 10 |
| 28°F | Sep 20 | Oct 4 | Oct 19 |
| 24°F | Sep 27 | Oct 13 | Oct 29 |
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 | 90 days | 109 days | 128 days |
| 32°F | 110 days | 129 days | 149 days |
| 28°F | 128 days | 149 days | 169 days |
| 24°F | 146 days | 169 days | 190 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 |
|---|---|---|---|
| 57730 | 5a | -20 to -15°F | 6 km |
| 57751 | 5a | -20 to -15°F | 18 km |
| 57773 | 5b | -15 to -10°F | 20 km |
| 57745 | 4b | -25 to -20°F | 30 km |
| 57702 | 5a | -20 to -15°F | 33 km |
| 57738 | 5a | -20 to -15°F | 38 km |
| 57747 | 5a | -20 to -15°F | 45 km |
| 57744 | 5a | -20 to -15°F | 46 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 USC00392087, at 43.7744, -103.6119, elevation 1670 m (5,480 ft).
- Data quality: Standard (24+ years of data), 26 years of freeze data.
- Average days per year at or below 32°F: 181.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Custer Co Airport (5 km)
- Mount Rushmore Nmem (17 km)
- Hill City (18 km)
- Wind Cave (27 km)
- Edgemont 23 NNW (30 km)
- Pactola Dam (34 km)
- Johnson Siding (37 km)
- Hot Springs (39 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.