| 2023 Hardiness Zone: | Zone 5b: -15°F to -10°F | |
| 2012 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 5b: -15°F to -10°F | |
| 1990 Hardiness Zone: | Zone 5a: -20F to -15F | |
| Average First Frost Date: | Oct. 11 - Oct. 20 | |
| Average Last Frost Date: | May 11 - May 20 | |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers | |
| Ecoregion: | 53a - Rock River Drift Plain | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 53545 - Janesville, WI | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 10 | 16 | 26 | 37 | 48 | 57 | 62 | 60 | 51 | 41 | 29 | 17 | 38 |
| Avg Max Temp (°F) | 27 | 33 | 44 | 58 | 71 | 80 | 84 | 82 | 74 | 62 | 45 | 32 | 58 |
| Avg Precip (In.) | 1.28 | 1.27 | 2.22 | 3.56 | 3.42 | 4.2 | 3.98 | 4.35 | 3.49 | 2.5 | 2.54 | 1.7 | 34.51 |