Fenwick, Connecticut has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 7.1 °C (low) to 15.8 °C (high). Annual precipitation averages 1249.4 Millimeters. Fenwick is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.2 °C | 3.9 °C | 93.47 mm |
| February | -3.7 °C | 4.6 °C | 84.33 mm |
| March | -0.5 °C | 8.1 °C | 116.84 mm |
| April | 4.4 °C | 14.3 °C | 116.84 mm |
| May | 9.4 °C | 19.3 °C | 94.49 mm |
| June | 14.8 °C | 24.2 °C | 108.46 mm |
| July | 18.6 °C | 27.6 °C | 86.11 mm |
| August | 18.4 °C | 26.8 °C | 106.17 mm |
| September | 14.9 °C | 23.9 °C | 109.47 mm |
| October | 9.4 °C | 18 °C | 117.09 mm |
| November | 4.1 °C | 12.2 °C | 100.84 mm |
| December | -0.6 °C | 7 °C | 115.32 mm |
| Annual | 7.1 °C | 15.8 °C | 1249.43 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |