Norwich, Connecticut has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 42.5 °F (low) to 62.1 °F (high). Annual precipitation averages 50.4 Inches. Norwich 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 20.8 °F | 38.4 °F | 3.8 in. |
| February | 22.6 °F | 41.1 °F | 3.44 in. |
| March | 29.8 °F | 48.5 °F | 4.78 in. |
| April | 39.6 °F | 60.5 °F | 4.62 in. |
| May | 49.3 °F | 70.8 °F | 3.54 in. |
| June | 58.6 °F | 79.4 °F | 3.99 in. |
| July | 64.9 °F | 84.6 °F | 3.59 in. |
| August | 63.2 °F | 83.3 °F | 4.4 in. |
| September | 55.1 °F | 76.0 °F | 4.53 in. |
| October | 44.0 °F | 64.8 °F | 4.81 in. |
| November | 34.6 °F | 53.8 °F | 4.09 in. |
| December | 27.0 °F | 43.9 °F | 4.77 in. |
| Annual | 42.5 °F | 62.1 °F | 50.36 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |