| 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: | Dfb - Humid Continental Mild Summer, Wet All Year | |
| Ecoregion: | 47c - Iowan Surface | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 55982 - Waltham, MN | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 3 | 10 | 22 | 34 | 47 | 57 | 61 | 58 | 49 | 37 | 23 | 9 | 34 |
| Avg Max Temp (°F) | 21 | 27 | 39 | 55 | 68 | 78 | 81 | 79 | 71 | 59 | 40 | 25 | 54 |
| Avg Precip (In.) | 1.01 | .72 | 1.86 | 3.12 | 3.92 | 4.24 | 4.49 | 4.53 | 3.3 | 2.34 | 2.03 | 1.05 | 32.61 |