Hartford, Wisconsin has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 35.8 °F (low) to 55.1 °F (high). Annual precipitation averages 35.1 Inches. Hartford is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 10.1 °F | 26.3 °F | 1.64 in. |
| February | 12.7 °F | 29.9 °F | 1.46 in. |
| March | 22.8 °F | 41.6 °F | 1.93 in. |
| April | 34.0 °F | 54.5 °F | 3.61 in. |
| May | 45.2 °F | 66.5 °F | 3.98 in. |
| June | 55.1 °F | 76.3 °F | 4.53 in. |
| July | 59.6 °F | 80.6 °F | 4.03 in. |
| August | 57.7 °F | 78.7 °F | 3.87 in. |
| September | 49.7 °F | 72.0 °F | 3.18 in. |
| October | 38.5 °F | 58.8 °F | 2.92 in. |
| November | 27.5 °F | 44.5 °F | 2.05 in. |
| December | 17.0 °F | 31.9 °F | 1.86 in. |
| Annual | 35.8 °F | 55.1 °F | 35.06 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |