| 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: | October 11 - 20 | |
| Average Last Frost Date: | May 1 - 10 | |
| 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 53546 - 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 | 52 | 42 | 29 | 17 | 38 |
| Avg Max Temp (°F) | 27 | 33 | 45 | 59 | 72 | 81 | 85 | 82 | 74 | 63 | 46 | 33 | 58 |
| Avg Precip (In.) | 1.27 | 1.23 | 2.23 | 3.65 | 3.43 | 4.22 | 3.96 | 4.42 | 3.52 | 2.54 | 2.6 | 1.74 | 34.8 |