The Aug. 10 storm hit Iowa hard but also caused damage in Illinois, Ohio, Minnesota and Indiana. The National Oceanic and Atmospheric Administration said it's currently the second-costliest U.S. disaster so far in 2020, although cost estimates for widespread wildfires along the West Coast aren't yet available.
What's a derecho? The violent weather phenomenon you've probably never heard of
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The storm, known as a derecho, generated winds of up to 140 mph (225 kph) that flattened millions of acres of crops. The derecho also knocked out power to half a million Iowa residents and damaged homes, trees and power lines. Four people died as the storm moved across the Midwest.
RELATED: 13 tornadoes hit greater Chicago area during derecho, NWS says
The most expensive disaster so far this year was Hurricane Laura, which caused $14 billion in damage when it hit the Gulf Coast in August, according to the NOAA research.
National Weather Service meteorologist Allan Curtis told the Des Moines Register that the derecho caused such extensive damage because it lasted for roughly 14 hours and hit crops when they were especially vulnerable. He said the damage would have been significantly less if the derecho had occurred in the spring before crops were tall enough to be caught by the wind.
WATCH: Police radar captures 90mph winds during derecho
Police radar captures winds of 90 mph during derecho
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"If you were looking to exert the most damage on corn crops when it comes to thunderstorms and heavy winds, when the derecho rolled through in August, it was the perfect time to do it," Curtis said.
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The U.S. Agriculture Department has estimated that Iowa farmers will be unable to harvest at least 850,000 acres (343,983 hectares) of crops this fall because of the damage.
WATCH: Derecho flattens corn field before harvest
Powerful derecho flattens corn fields weeks before harvest