West Haven, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.9 °C (low) to 16 °C (high). Annual precipitation averages 1223.5 Millimeters. West Haven is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.9 °C | 3.6 °C | 95 mm |
| February | -4.2 °C | 4.7 °C | 78.74 mm |
| March | -0.4 °C | 8.4 °C | 111.76 mm |
| April | 4.9 °C | 14.4 °C | 106.93 mm |
| May | 10.4 °C | 19.9 °C | 97.79 mm |
| June | 15.7 °C | 24.9 °C | 105.66 mm |
| July | 19.1 °C | 28.2 °C | 88.14 mm |
| August | 18.4 °C | 27.3 °C | 100.84 mm |
| September | 14.5 °C | 24.1 °C | 109.73 mm |
| October | 8.2 °C | 17.8 °C | 121.67 mm |
| November | 2.7 °C | 11.8 °C | 96.27 mm |
| December | -1.7 °C | 6.4 °C | 111 mm |
| Annual | 6.9 °C | 16 °C | 1223.53 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 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 | Dfa - Humid Continental Hot Summers With Year Around Precipitation |