Watertown, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39 °F (low) to 60.4 °F (high). Annual precipitation averages 51.8 Inches. Watertown is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.4 °F | 35.9 °F | 3.56 in. |
| February | 18.6 °F | 38.9 °F | 3.12 in. |
| March | 25.7 °F | 46.9 °F | 4.29 in. |
| April | 36.2 °F | 59.4 °F | 3.98 in. |
| May | 46.4 °F | 70.4 °F | 4.12 in. |
| June | 55.6 °F | 78.6 °F | 4.61 in. |
| July | 61.1 °F | 83.5 °F | 4.83 in. |
| August | 59.5 °F | 81.6 °F | 4.65 in. |
| September | 52.3 °F | 74.5 °F | 4.72 in. |
| October | 40.7 °F | 62.7 °F | 5.38 in. |
| November | 31.3 °F | 51.3 °F | 3.99 in. |
| December | 23.5 °F | 40.7 °F | 4.54 in. |
| Annual | 39 °F | 60.4 °F | 51.79 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |