| 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 4b: -25°F to -20°F Zone 4a: -30°F to -25°F |
| 1990 Hardiness Zone: | Zone 3b: -35F to -30F |
| 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: | 51b - Central Wisconsin Undulating Till Plain |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 54452 - Merrill, WI | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 0 | 4 | 16 | 30 | 41 | 51 | 56 | 54 | 44 | 34 | 22 | 7 | 30 |
| Avg Max Temp (°F) | 21 | 27 | 38 | 53 | 67 | 75 | 79 | 77 | 68 | 56 | 39 | 25 | 52 |
| Avg Precip (In.) | 1.14 | .9 | 1.83 | 2.66 | 3.31 | 3.87 | 3.91 | 4.33 | 4.28 | 2.59 | 2.31 | 1.38 | 32.49 |