Lebanon, Connecticut has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 39.7 °F (low) to 59.9 °F (high). Annual precipitation averages 49.7 Inches. Lebanon 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 | 18.3 °F | 36.1 °F | 3.82 in. |
| February | 19.6 °F | 38.8 °F | 3.3 in. |
| March | 26.9 °F | 46.5 °F | 4.6 in. |
| April | 36.7 °F | 58.6 °F | 4.44 in. |
| May | 46.5 °F | 68.8 °F | 3.53 in. |
| June | 55.7 °F | 77.2 °F | 4.03 in. |
| July | 61.8 °F | 82.3 °F | 3.85 in. |
| August | 60.1 °F | 80.9 °F | 4.25 in. |
| September | 52.5 °F | 73.7 °F | 4.33 in. |
| October | 41.7 °F | 62.5 °F | 4.87 in. |
| November | 32.3 °F | 51.5 °F | 4.03 in. |
| December | 24.6 °F | 41.6 °F | 4.66 in. |
| Annual | 39.7 °F | 59.9 °F | 49.71 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 | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |