Andover, Connecticut has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 39.3 °F (low) to 59.7 °F (high). Annual precipitation averages 49.3 Inches. Andover is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.6 °F | 35.9 °F | 3.58 in. |
| February | 19.0 °F | 38.5 °F | 3.1 in. |
| March | 26.6 °F | 46.2 °F | 4.35 in. |
| April | 36.6 °F | 58.3 °F | 4.29 in. |
| May | 46.4 °F | 68.7 °F | 3.63 in. |
| June | 55.7 °F | 77.1 °F | 4.31 in. |
| July | 61.5 °F | 82.2 °F | 4.02 in. |
| August | 59.7 °F | 80.7 °F | 4.37 in. |
| September | 52.1 °F | 74.0 °F | 4.5 in. |
| October | 40.9 °F | 62.3 °F | 4.84 in. |
| November | 31.6 °F | 51.4 °F | 3.87 in. |
| December | 23.8 °F | 41.5 °F | 4.41 in. |
| Annual | 39.3 °F | 59.7 °F | 49.27 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |