Charlestown, Rhode Island has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 44.1 °F (low) to 59.1 °F (high). Annual precipitation averages 49.1 Inches. Charlestown is located in USDA Plant Hardiness Zone 7a. 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 | 23.8 °F | 38.4 °F | 4.05 in. |
| February | 24.9 °F | 39.9 °F | 3.59 in. |
| March | 30.6 °F | 45.7 °F | 5.21 in. |
| April | 39.5 °F | 55.3 °F | 4.62 in. |
| May | 48.7 °F | 64.7 °F | 3.49 in. |
| June | 58.3 °F | 73.6 °F | 3.75 in. |
| July | 64.5 °F | 79.4 °F | 3.07 in. |
| August | 63.9 °F | 78.7 °F | 3.78 in. |
| September | 58.2 °F | 73.1 °F | 3.71 in. |
| October | 48.0 °F | 62.9 °F | 4.75 in. |
| November | 38.3 °F | 53.1 °F | 4.18 in. |
| December | 30.2 °F | 44.1 °F | 4.89 in. |
| Annual | 44.1 °F | 59.1 °F | 49.09 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 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 | Dfb - Humid Continental Mild Summer, Wet All Year |