Collinsville, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.2 °C (low) to 15.8 °C (high). Annual precipitation averages 1341.1 Millimeters. Collinsville is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.1 °C | 1.8 °C | 93.22 mm |
| February | -7.4 °C | 3.6 °C | 84.58 mm |
| March | -3.2 °C | 8.1 °C | 106.93 mm |
| April | 2.6 °C | 15.3 °C | 102.36 mm |
| May | 8.4 °C | 21.4 °C | 104.14 mm |
| June | 13.7 °C | 26.1 °C | 120.14 mm |
| July | 16.6 °C | 29 °C | 119.38 mm |
| August | 15.6 °C | 27.8 °C | 122.17 mm |
| September | 11.5 °C | 23.9 °C | 126.75 mm |
| October | 5.2 °C | 17.1 °C | 142.75 mm |
| November | -0.2 °C | 10.7 °C | 101.09 mm |
| December | -4.6 °C | 4.8 °C | 117.6 mm |
| Annual | 4.2 °C | 15.8 °C | 1341.11 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |