Watertown, Wisconsin has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.3 °F (low) to 56.4 °F (high). Annual precipitation averages 36.4 Inches. Watertown 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 | 11.1 °F | 27.0 °F | 1.43 in. |
| February | 13.5 °F | 30.6 °F | 1.44 in. |
| March | 24.2 °F | 42.7 °F | 1.93 in. |
| April | 35.7 °F | 56.2 °F | 3.66 in. |
| May | 47.3 °F | 68.5 °F | 4.09 in. |
| June | 57.5 °F | 78.2 °F | 5.34 in. |
| July | 61.5 °F | 82.0 °F | 4.29 in. |
| August | 59.6 °F | 80.2 °F | 4.04 in. |
| September | 51.4 °F | 73.6 °F | 3.39 in. |
| October | 39.9 °F | 60.2 °F | 2.94 in. |
| November | 28.5 °F | 45.4 °F | 2.13 in. |
| December | 17.9 °F | 32.5 °F | 1.73 in. |
| Annual | 37.3 °F | 56.4 °F | 36.41 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |