South Royalton, Vermont has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 33.5 °F (low) to 56.4 °F (high). Annual precipitation averages 41.3 Inches. South Royalton is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.9 °F | 28.8 °F | 2.86 in. |
| February | 9.1 °F | 32.5 °F | 2.36 in. |
| March | 18.6 °F | 41.1 °F | 2.96 in. |
| April | 30.7 °F | 55.2 °F | 3.18 in. |
| May | 42.6 °F | 68.7 °F | 3.38 in. |
| June | 51.7 °F | 77.0 °F | 4.32 in. |
| July | 57.0 °F | 81.8 °F | 4.46 in. |
| August | 55.3 °F | 79.7 °F | 3.85 in. |
| September | 48.0 °F | 72.9 °F | 3.4 in. |
| October | 36.7 °F | 59.1 °F | 4.01 in. |
| November | 27.1 °F | 46.1 °F | 3.06 in. |
| December | 16.7 °F | 34.0 °F | 3.48 in. |
| Annual | 33.5 °F | 56.4 °F | 41.32 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |