Egan, South Dakota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 1.1 °C (low) to 12.5 °C (high). Annual precipitation averages 706.1 Millimeters. Egan 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 Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -15.1 °C | -4.9 °C | 14.48 mm |
| February | -13 °C | -2.2 °C | 19.56 mm |
| March | -6.3 °C | 4.7 °C | 35.05 mm |
| April | 0.4 °C | 12.7 °C | 69.34 mm |
| May | 7.7 °C | 19.6 °C | 94.49 mm |
| June | 13.9 °C | 25.2 °C | 113.03 mm |
| July | 16.2 °C | 27.7 °C | 89.66 mm |
| August | 14.6 °C | 26.3 °C | 87.63 mm |
| September | 9.5 °C | 22.6 °C | 78.49 mm |
| October | 1.9 °C | 14.8 °C | 55.37 mm |
| November | -5.4 °C | 5.6 °C | 26.92 mm |
| December | -11.8 °C | -2.2 °C | 22.1 mm |
| Annual | 1.1 °C | 12.5 °C | 706.12 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |