Foster, Rhode Island has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 39.4 °F (low) to 58.3 °F (high). Annual precipitation averages 53 Inches. Foster 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 | 18.7 °F | 35.1 °F | 4.3 in. |
| February | 19.3 °F | 37.4 °F | 3.66 in. |
| March | 26.2 °F | 44.8 °F | 5.05 in. |
| April | 36.0 °F | 57.4 °F | 4.72 in. |
| May | 45.9 °F | 68.0 °F | 3.7 in. |
| June | 55.2 °F | 75.2 °F | 4.43 in. |
| July | 60.9 °F | 80.7 °F | 3.76 in. |
| August | 59.5 °F | 78.7 °F | 4.48 in. |
| September | 52.6 °F | 71.7 °F | 4.26 in. |
| October | 41.9 °F | 60.4 °F | 5.13 in. |
| November | 32.3 °F | 50.0 °F | 4.36 in. |
| December | 24.2 °F | 39.9 °F | 5.1 in. |
| Annual | 39.4 °F | 58.3 °F | 52.95 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 | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |