Norfolk, Connecticut has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 36.7 °F (low) to 56.7 °F (high). Annual precipitation averages 52.9 Inches. Norfolk is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 14.0 °F | 31.7 °F | 3.87 in. |
| February | 15.4 °F | 34.6 °F | 3.33 in. |
| March | 23.0 °F | 42.5 °F | 4.15 in. |
| April | 33.7 °F | 56.3 °F | 3.9 in. |
| May | 44.5 °F | 67.5 °F | 4.12 in. |
| June | 53.9 °F | 75.4 °F | 4.93 in. |
| July | 58.9 °F | 80.2 °F | 4.77 in. |
| August | 57.9 °F | 78.5 °F | 4.72 in. |
| September | 50.4 °F | 70.9 °F | 4.96 in. |
| October | 38.9 °F | 59.0 °F | 5.25 in. |
| November | 29.5 °F | 47.4 °F | 4.08 in. |
| December | 20.8 °F | 36.6 °F | 4.83 in. |
| Annual | 36.7 °F | 56.7 °F | 52.91 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |