Hamden, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.1 °C (low) to 16 °C (high). Annual precipitation averages 1317.3 Millimeters. Hamden 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. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.8 °C | 2.6 °C | 98.3 mm |
| February | -6.1 °C | 4.1 °C | 86.36 mm |
| March | -2.1 °C | 8.3 °C | 113.03 mm |
| April | 3.5 °C | 15 °C | 111.51 mm |
| May | 9 °C | 21.1 °C | 105.66 mm |
| June | 14.3 °C | 25.7 °C | 116.59 mm |
| July | 17.4 °C | 28.8 °C | 106.43 mm |
| August | 16.6 °C | 27.8 °C | 105.66 mm |
| September | 12.6 °C | 24.1 °C | 118.11 mm |
| October | 6 °C | 17.5 °C | 136.14 mm |
| November | 0.7 °C | 11.1 °C | 101.35 mm |
| December | -3.6 °C | 5.4 °C | 118.11 mm |
| Annual | 5.1 °C | 16 °C | 1317.25 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |