Glenville, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 44.9 °F (low) to 61.7 °F (high). Annual precipitation averages 49.7 Inches. Glenville is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 23.8 °F | 38.6 °F | 3.98 in. |
| February | 24.7 °F | 40.8 °F | 2.9 in. |
| March | 31.4 °F | 47.8 °F | 4.15 in. |
| April | 41.3 °F | 60.0 °F | 4.04 in. |
| May | 51.1 °F | 70.0 °F | 3.79 in. |
| June | 60.6 °F | 78.9 °F | 4.58 in. |
| July | 66.1 °F | 84.3 °F | 3.99 in. |
| August | 65.4 °F | 82.2 °F | 4.62 in. |
| September | 58.5 °F | 75.7 °F | 4.8 in. |
| October | 47.8 °F | 64.6 °F | 4.49 in. |
| November | 38.2 °F | 53.7 °F | 3.91 in. |
| December | 30.3 °F | 44.0 °F | 4.41 in. |
| Annual | 44.9 °F | 61.7 °F | 49.66 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |