Rockville, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.2 °F (low) to 59.4 °F (high). Annual precipitation averages 47.7 Inches. Rockville 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 | 17.1 °F | 35.1 °F | 3.39 in. |
| February | 18.3 °F | 37.6 °F | 2.98 in. |
| March | 26.3 °F | 45.5 °F | 4.14 in. |
| April | 36.6 °F | 58.0 °F | 3.99 in. |
| May | 46.6 °F | 68.8 °F | 3.62 in. |
| June | 55.9 °F | 77.1 °F | 4.28 in. |
| July | 61.4 °F | 82.3 °F | 4.06 in. |
| August | 59.7 °F | 80.7 °F | 4.2 in. |
| September | 52.3 °F | 74.0 °F | 4.41 in. |
| October | 40.9 °F | 62.1 °F | 4.72 in. |
| November | 31.5 °F | 50.8 °F | 3.67 in. |
| December | 23.5 °F | 40.7 °F | 4.28 in. |
| Annual | 39.2 °F | 59.4 °F | 47.74 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 | Dfa - Humid Continental Hot Summers With Year Around Precipitation |