Derby, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42.3 °F (low) to 60.8 °F (high). Annual precipitation averages 51 Inches. Derby 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 | 20.6 °F | 37.3 °F | 3.82 in. |
| February | 21.9 °F | 39.5 °F | 3.39 in. |
| March | 29.3 °F | 46.8 °F | 4.6 in. |
| April | 39.4 °F | 58.3 °F | 4.3 in. |
| May | 49.5 °F | 69.5 °F | 4.12 in. |
| June | 58.9 °F | 77.8 °F | 4.49 in. |
| July | 64.6 °F | 83.7 °F | 3.82 in. |
| August | 63.0 °F | 81.9 °F | 4.1 in. |
| September | 55.9 °F | 75.8 °F | 4.89 in. |
| October | 44.0 °F | 64.1 °F | 4.88 in. |
| November | 34.3 °F | 52.6 °F | 4.13 in. |
| December | 26.4 °F | 42.5 °F | 4.44 in. |
| Annual | 42.3 °F | 60.8 °F | 50.98 in. |
| 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 : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |