| 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 53548 - Janesville, WI | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 9 | 15 | 25 | 36 | 48 | 57 | 62 | 59 | 51 | 40 | 28 | 16 | 37 |
| Avg Max Temp (°F) | 26 | 32 | 44 | 58 | 71 | 80 | 83 | 81 | 73 | 62 | 45 | 32 | 57 |
| Avg Precip (In.) | 1.29 | 1.28 | 2.22 | 3.53 | 3.45 | 4.25 | 3.99 | 4.32 | 3.48 | 2.5 | 2.51 | 1.69 | 34.52 |