Waterbury, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.3 °F (low) to 61 °F (high). Annual precipitation averages 52.3 Inches. Waterbury 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 18.8 °F | 36.5 °F | 3.85 in. |
| February | 20.0 °F | 39.2 °F | 3.31 in. |
| March | 27.3 °F | 47.1 °F | 4.57 in. |
| April | 37.4 °F | 59.6 °F | 4.18 in. |
| May | 47.6 °F | 70.7 °F | 4.15 in. |
| June | 56.9 °F | 79.0 °F | 4.57 in. |
| July | 62.4 °F | 84.4 °F | 4.5 in. |
| August | 60.8 °F | 82.4 °F | 4.37 in. |
| September | 53.5 °F | 75.5 °F | 4.66 in. |
| October | 42.0 °F | 63.6 °F | 5.36 in. |
| November | 32.4 °F | 51.9 °F | 4.13 in. |
| December | 24.6 °F | 41.5 °F | 4.63 in. |
| Annual | 40.3 °F | 61 °F | 52.28 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 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 |