On this date — December 15, 2021 — Iowa experienced a weather event that redefined what’s possible in December: a historic, record-shattering derecho.
It became the first derecho ever recorded anywhere in the United States during the month of December and prompted the first December Moderate Risk for severe thunderstorms ever issued by the Storm Prediction Center for Iowa. The event caused over $1 billion in damage and produced 120 tornadoes across Nebraska, Iowa, Minnesota, and Wisconsin.
Iowa alone saw 63 tornadoes in a single day, the most ever recorded, accounting for more than half of the state’s 2021 tornado total. Of those, 21 were EF2 or stronger, also a single-day record. Before this storm, Iowa had only seen five December tornadoes total since 1950.
The system also brought extreme winds, including an 88 mph thunderstorm gust in Audubon, a 108 mph tornado gust near Sheffield, and the strongest non-thunderstorm wind gust at Des Moines International Airport in over 50 years. Adding to the rarity, the storm shattered Iowa’s all-time December high-temperature record, reaching 75°F in several cities.