Cromwell, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.3 °F (low) to 60.7 °F (high). Annual precipitation averages 50.6 Inches. Cromwell 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 | 19.6 °F | 36.3 °F | 3.77 in. |
| February | 20.8 °F | 38.9 °F | 3.28 in. |
| March | 28.4 °F | 46.8 °F | 4.41 in. |
| April | 38.5 °F | 59.4 °F | 4.19 in. |
| May | 48.6 °F | 70.1 °F | 3.79 in. |
| June | 58.0 °F | 78.7 °F | 4.86 in. |
| July | 63.5 °F | 84.2 °F | 4.17 in. |
| August | 61.9 °F | 82.5 °F | 4.16 in. |
| September | 54.5 °F | 75.2 °F | 4.46 in. |
| October | 43.1 °F | 63.1 °F | 5.18 in. |
| November | 33.4 °F | 51.8 °F | 3.91 in. |
| December | 25.4 °F | 41.7 °F | 4.46 in. |
| Annual | 41.3 °F | 60.7 °F | 50.64 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |