Jefferson, Wisconsin has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.7 °F (low) to 57.1 °F (high). Annual precipitation averages 37.1 Inches. Jefferson is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.4 °F | 27.5 °F | 1.55 in. |
| February | 14.2 °F | 31.3 °F | 1.52 in. |
| March | 24.9 °F | 43.5 °F | 2.07 in. |
| April | 36.1 °F | 56.8 °F | 3.83 in. |
| May | 47.7 °F | 69.3 °F | 4.13 in. |
| June | 57.7 °F | 79.2 °F | 5.28 in. |
| July | 61.8 °F | 82.8 °F | 4.17 in. |
| August | 59.9 °F | 80.9 °F | 4.14 in. |
| September | 51.6 °F | 74.1 °F | 3.44 in. |
| October | 40.1 °F | 60.9 °F | 2.96 in. |
| November | 28.8 °F | 45.8 °F | 2.22 in. |
| December | 18.4 °F | 32.9 °F | 1.82 in. |
| Annual | 37.7 °F | 57.1 °F | 37.13 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |