| 2023 Hardiness Zone: | Zone 4b: -25°F to -20°F 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 3b: -35F to -30F |
| Average First Frost Date: | Oct. 1 - Oct. 10 |
| Average Last Frost Date: | May 11 - May 20 |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year |
| Ecoregion: | 51a - St. Croix Outwash Plain |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 54840 - Grantsburg, WI | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | -3 | 4 | 17 | 31 | 43 | 52 | 57 | 55 | 45 | 34 | 20 | 4 | 30 |
| Avg Max Temp (°F) | 19 | 27 | 39 | 55 | 69 | 76 | 80 | 78 | 68 | 56 | 38 | 24 | 52 |
| Avg Precip (In.) | 1.13 | .83 | 1.72 | 2.17 | 3.46 | 4.46 | 4.29 | 4.49 | 3.48 | 2.45 | 2.08 | 1.09 | 31.65 |