What Is a Derecho? The Inland Hurricane Explained
A derecho (deh-REY-cho, Spanish for "straight ahead") is a widespread, long-lived windstorm produced by a fast-moving line of severe thunderstorms. To qualify, the wind damage swath must extend more than 400 miles with gusts of at least 58 mph along most of its length — but strong derechos deliver gusts of 75–100+ mph, which is why they're nicknamed "inland hurricanes."
How they form
The engine is a bow echo: rain-cooled air crashes down from a squall line, spreads along the ground, and shoves the line forward in an accelerating arc. When atmospheric conditions — usually hot, very humid air along a stalled front — keep regenerating that cycle for hours, the storm complex can race across several states at 50–70 mph.
Why they're so damaging
Unlike a tornado's narrow path, derecho winds hit everything across a front dozens of miles wide for minutes at a time. The August 2020 Midwest derecho produced estimated 140 mph gusts in Iowa, flattened roughly a third of the state's corn crop, and caused about $11 billion in damage — the costliest thunderstorm event in US history.
Warning signs
Derechos usually announce themselves as a Severe Thunderstorm Warning with "destructive" wind tags — the kind that triggers phone alerts. On radar, watch for a bowing line racing toward you; on our live map, a chain of severe thunderstorm warnings lighting up along a line is the classic signature. Treat a derecho warning like a hurricane's arrival: get inside, away from windows, before the gust front hits.
FAQ
How is a derecho different from a tornado?
Tornado winds rotate and cut a narrow path; derecho winds blow in straight lines across a swath that can be 50+ miles wide and hundreds of miles long. Damage patterns point the same direction — that's how surveys tell them apart.
How strong are derecho winds?
By definition gusts reach at least 58 mph along the path; strong derechos produce 75–100+ mph, and the 2020 Iowa derecho was estimated at 140 mph — Category 4 hurricane speeds.
What should I do when a derecho is coming?
Treat it like a brief hurricane: get indoors immediately, stay away from windows, and expect power outages. Derechos travel 50–70 mph, so the time between the warning and the gust front can be minutes.