Terryville, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.7 °C (low) to 15.7 °C (high). Annual precipitation averages 1359.9 Millimeters. Terryville is located in USDA Plant Hardiness Zone 6a. 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 | -8.4 °C | 1.9 °C | 97.03 mm |
| February | -7.7 °C | 3.6 °C | 84.58 mm |
| March | -3.7 °C | 7.9 °C | 118.62 mm |
| April | 2.1 °C | 15.3 °C | 105.41 mm |
| May | 7.8 °C | 21.3 °C | 107.44 mm |
| June | 12.9 °C | 26 °C | 117.86 mm |
| July | 15.9 °C | 28.7 °C | 120.9 mm |
| August | 15.1 °C | 27.6 °C | 118.11 mm |
| September | 11 °C | 23.6 °C | 121.67 mm |
| October | 4.7 °C | 16.9 °C | 142.75 mm |
| November | -0.6 °C | 10.5 °C | 105.66 mm |
| December | -4.9 °C | 4.6 °C | 119.89 mm |
| Annual | 3.7 °C | 15.7 °C | 1359.92 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |