Webster, South Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 33.2 °F (low) to 52.5 °F (high). Annual precipitation averages 25.1 Inches. Webster is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.6 °F | 20.4 °F | 0.77 in. |
| February | 6.5 °F | 25.4 °F | 0.73 in. |
| March | 18.4 °F | 37.3 °F | 1.09 in. |
| April | 31.7 °F | 52.7 °F | 2.34 in. |
| May | 45.1 °F | 66.2 °F | 3.19 in. |
| June | 56.2 °F | 75.8 °F | 3.99 in. |
| July | 60.9 °F | 80.7 °F | 3.94 in. |
| August | 59.0 °F | 79.3 °F | 2.67 in. |
| September | 50.1 °F | 71.4 °F | 2.51 in. |
| October | 36.2 °F | 56.1 °F | 2.36 in. |
| November | 22.1 °F | 39.2 °F | 0.65 in. |
| December | 9.8 °F | 25.8 °F | 0.89 in. |
| Annual | 33.2 °F | 52.5 °F | 25.13 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |