What Is a Derecho?
A derecho (deh-RAY-cho) is a widespread, long-lived windstorm associated with a fast-moving band of severe thunderstorms. To officially qualify as a derecho, the swath of wind damage must extend at least 250 miles with wind gusts of 58 mph or greater along most of its length.
Derechos produce straight-line winds — the wind blows in one direction, unlike a tornado's rotation. But those winds can reach 80–130 mph over a path hundreds of miles long and tens of miles wide, flattening everything in their way.
The June 2012 derecho hit from Indiana to the mid-Atlantic coast, leaving 4.2 million people without power. The August 2020 Midwest derecho caused $11 billion in damage across Iowa in under an hour.
Key Differences
Wind Direction
Tornado: Rotating winds spiral inward. Damage is twisted and scattered in different directions.
Derecho: Straight-line winds. Trees and structures fall in the same direction.
Size of Damage Path
Tornado: Narrow path, typically 100 yards to a mile wide, up to a few dozen miles long.
Derecho: 50–100+ miles wide and 250–500+ miles long. A single event can affect multiple states.
Duration
Tornado: Most last 10–20 minutes on the ground. Even long-track tornadoes rarely exceed an hour.
Derecho: The storm system can last 6–12+ hours as it races across hundreds of miles. The wind at any one location lasts 10–30 minutes.
Alerts
Tornado: NWS issues a Tornado Warning with a specific polygon.
Derecho: Severe Thunderstorm Warnings with "destructive" damage tags and/or Tornado Warnings for embedded rotation. There is no "Derecho Warning" — the NWS warns for each cell individually.
Why Derechos Are Underestimated
No Dedicated Warning
People hear "severe thunderstorm" and think rain and lightning. A derecho-producing line can be catastrophic, but the warning language doesn't always convey the severity.
They Move Fast
Derechos travel at 50–70 mph. By the time you see the shelf cloud on the horizon, you may have 10–15 minutes before 100 mph winds arrive.
Trees Are the Killer
Most derecho fatalities come from trees falling on cars, homes, and people. The wider damage path means far more trees affected than a typical tornado.
How Derechos Form
Derechos typically develop from a cluster of thunderstorms that organizes into a bow echo — a line of storms that bulges forward in the middle as a concentrated pocket of descending air (a rear-inflow jet) accelerates that section of the line faster than the rest. On radar, this produces the telltale bowed-out shape the phenomenon is named for. Derechos are most common in the warm season (May through August) in the corridor from the upper Midwest through the Ohio Valley and mid-Atlantic, though they can occur anywhere sufficiently unstable, wind-sheared air sets up ahead of a fast-moving line of storms.
Frequently Asked Questions
Is a derecho the same as a "land hurricane"?
That's an informal nickname sometimes used because of the widespread wind damage, but a derecho is not a tropical system — it forms from a line of thunderstorms, not a warm-core rotating storm, and has no eye or spiral structure.
Can a derecho produce tornadoes too?
Yes. Individual cells embedded within a derecho-producing line can rotate and spawn tornadoes, which is why NWS may issue Tornado Warnings for specific segments of the line even as the broader event is straight-line wind.
How much warning do you get before a derecho hits?
Often 30–60 minutes from the first Severe Thunderstorm Warning covering your area, though the visible shelf cloud may only be visible 10–15 minutes before arrival given how fast these systems move.
Do derechos happen outside the US?
Yes, the phenomenon (and the term, borrowed from Spanish for "straight") occurs globally wherever the right combination of instability and wind shear sets up ahead of a fast-moving line of storms, though it's most studied and most frequently documented in the central and eastern US.
Stay Ahead of Both
StormCast delivers all NWS severe thunderstorm and tornado warnings to your phone within moments. Whether it's a supercell tornado or a derecho, you'll know before it arrives.
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A note on this guide: Thresholds and criteria described here are general and can vary by NWS forecast office, region, and over time. This content is educational — always check your local National Weather Service office for the specific criteria that apply to your area.