
Average annual precipitation in South Dakota ranges from semi-arid in the northwestern part of the state (around 15 inches, or 381 mm) to semi-humid around the southeast portion of the state (around 25 inches, or 635 mm), although a small area centered around Lead in the Black Hills has the highest precipitation at nearly 30 inches (762 mm) per year.
South Dakota summers bring frequent, sometimes severe, thunderstorms with high winds, thunder, and hail. The eastern part of the state is often considered part of Tornado Alley, and South Dakota experiences an average of 29 tornadoes per year. Winters are somewhat more stable, although severe weather in the form of blizzards and ice storms can occur during the season.