| 2023 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 4b: -25°F to -20°F | |
| 2012 Hardiness Zone: | Zone 4b: -25°F to -20°F | |
| 1990 Hardiness Zone: | Zone 4b: -25F to -20F | |
| Average First Frost Date: | Oct. 1 - Oct. 10 | |
| Average Last Frost Date: | May 11 - May 20 | |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers | |
| Ecoregion: | 43c - River Breaks | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 31 - 45 days Over 86°F |
Annual Climate Data for ZIP Code 57339 - Fort Thompson, SD | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 5 | 12 | 22 | 34 | 46 | 56 | 62 | 60 | 49 | 36 | 22 | 10 | 34 |
| Avg Max Temp (°F) | 27 | 34 | 45 | 60 | 72 | 82 | 89 | 87 | 78 | 63 | 43 | 31 | 59 |
| Avg Precip (In.) | .38 | .48 | 1.3 | 2.04 | 3 | 3.04 | 2.72 | 2.06 | 1.63 | 1.62 | .68 | .39 | 19.37 |