| 2023 Hardiness Zone: | Zone 4a: -30°F to -25°F |
| 2012 Hardiness Zone: | Zone 3b: -35°F to -30°F Zone 4a: -30°F to -25°F |
| 1990 Hardiness Zone: | Zone 4a: -30F to -25F |
| Average First Frost Date: | Sep. 21 - Sep. 30 |
| Average Last Frost Date: | May 21 - May 31 |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year |
| Ecoregion: | 48a - Glacial Lake Agassiz Basin |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 58237 - Grafton, ND | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | -5 | 2 | 16 | 30 | 44 | 53 | 57 | 54 | 45 | 33 | 17 | 2 | 29 |
| Avg Max Temp (°F) | 13 | 21 | 34 | 53 | 69 | 78 | 81 | 81 | 69 | 55 | 33 | 18 | 50 |
| Avg Precip (In.) | .54 | .49 | .85 | 1.16 | 2.3 | 3.3 | 2.83 | 2.4 | 1.78 | 1.47 | .89 | .44 | 18.45 |