A derecho is a large cluster of thunderstorms that most commonly forms in the late spring and summer and causes widespread destruction to trees, power lines and sometimes homes and buildings. 

What 'derecho' means

From the Spanish word for “straight,” these windstorms leave wide, long areas of straight-line wind damage. 

Winds can be as strong as 60 to 100 mph or higher in extreme cases.

They have a distinct look on radar, usually as one or more curved lines of thunderstorms known as a bow echo.

A 2026 study by Squitieri found that nearly 47% of derechos within the 70 years they examined measured wind gusts greater than 100 mph.

Their damage is widespread

A single severe thunderstorm may produce an area of damaging winds only a mile or two wide and maybe a few miles long, but derechos can produce damage tens of miles wide and hundreds of miles long.

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To be called a derecho, the thunderstorm-generated high winds and wind damage should cover a distance of at least 250 miles long and produce at least a handful of 74-plus-mph wind gusts, according to a January 2025 proposal led by Brian Squitieri.

Recovery can take days to weeks

In the worst derecho events, relief workers from other states are sometimes needed to aid in these efforts due to the scope of damage and outages.

On Aug. 10, 2020, a derecho in the Midwest caused an estimated $13.5 billion in damage as it raked across parts of eight states. Power was knocked out to almost 2 million homes and businesses, and some didn’t have power restored for weeks.

When and where do they happen most?

Derechos in the U.S. are most numerous in the warm-season months. The 2026 study found that the majority of derechos since 1955 occurred in June and July, followed by May and August.  

They also found that most derecho wind swaths begin around or after afternoon peak heating, typically lasting six to 14 hours.

In rarer cases, multiple derechos can affect an area within 24 to 48 hours if the weather pattern is stubborn enough.

Anywhere east of the Rockies can see a derecho, but the most favorable corridors for derechos are the Midwest-Ohio Valley, Southern Plains and Northern Plains.

According to a 2016 study, a distinct corridor from the upper Mississippi Valley through the Ohio Valley is most susceptible to derechos.

They can be deadly

A 2005 study by Walker Ashley and Thomas Mote found that derechos claimed 153 lives in the 18-year period of their study. Three northern states – New York (23), Michigan (17) and Ohio (16) – comprised over a third of all derecho deaths.

The Squitieri et al. recent study found 47% percent of derecho fatalities were caused by fallen trees or tree branches.

How to stay safe

As with any severe weather situation, planning ahead and staying informed are key.

First, know where you'll seek safe shelter if a National Weather Service warning is issued. If you live in a mobile or manufactured home, find either a sturdy building or community shelter ahead of time and know how to reach it quickly. A derecho's strongest winds can heavily damage or blow over a mobile home.

Next, have multiple ways to receive NWS warnings, including by smartphone and from NOAA weather radio. These are two sources that can also wake you if a warning is issued while you're sleeping. Make sure each is charged fully before the storms arrive.

Move to shelter immediately when a warning is issued, including both severe thunderstorm and tornado warnings.

Miriam Guthrie is an associate meteorologist with weather.com who graduated from Georgia Tech with her undergrad and graduate degrees in Earth & Atmospheric Sciences.