Swansea, Massachusetts has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.8 °F (low) to 60.2 °F (high). Annual precipitation averages 50.5 Inches. Swansea is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 22.4 °F | 38.1 °F | 4.27 in. |
| February | 23.6 °F | 39.8 °F | 3.64 in. |
| March | 30.1 °F | 46.5 °F | 5.36 in. |
| April | 40.0 °F | 57.3 °F | 4.57 in. |
| May | 49.4 °F | 67.6 °F | 3.51 in. |
| June | 59.4 °F | 76.3 °F | 4.02 in. |
| July | 65.7 °F | 82.3 °F | 3.48 in. |
| August | 64.6 °F | 81.0 °F | 3.7 in. |
| September | 57.8 °F | 74.4 °F | 3.95 in. |
| October | 46.6 °F | 63.0 °F | 4.74 in. |
| November | 37.0 °F | 52.7 °F | 4.36 in. |
| December | 28.7 °F | 43.4 °F | 4.92 in. |
| Annual | 43.8 °F | 60.2 °F | 50.52 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |