Thunderstorm Safety and Preparedness

It's the Peak Time For Damaging Thunderstorm Winds, Including Derechos

Average number of severe wind/damaging wind reports from thunderstorms May to August from 2000 through 2021. There is a peak in the number of reports during June and July.
(Data: NOAA/NWS/SPC)

At a Glance

June and July are the peak months for high winds from severe thunderstorms in the United States.
Much of the country is prone to this threat.
Derechos are an example of a widespread wind damage event that can occur in summer.

We are now in the annual peak for damaging winds from severe thunderstorms across the United States, which are sometimes from widespread destructive wind events called derechos.

June and July have both averaged close to 3,000 severe wind reports annually since 2000, according to data compiled by NOAA's Storm Prediction Center.

A thunderstorm can produce a severe wind report if there's a measured wind gust of 58 mph or greater, or if there are reports of damage to structures, trees or power lines caused by straight-line winds.

You can see in the graph above how the average number of reports from June and July stands well above the next closest months of May and August. All other months typically have lower severe wind reports overall compared to May through August.

June 2008 (5,445 reports) and July 2016 (4,642 reports) are the months with the most severe wind reports dating to 2000. June and July are the only months that have logged more than 4,000 severe thunderstorm wind reports.

Why It's the Peak Time of Year

The reason for the June and July peak is fairly straightforward. Warm and humid air is most widespread and abundant east of the Rockies during this time of year, one condition favorable for thunderstorm development.

The jet stream, which flows from west to east near the Canadian border in summer, sends disturbances over the top of this warm, humid air, fueling thunderstorm development throughout the nation's northern tier.

Sometimes, that weather pattern spawns thunderstorm complexes with widespread areas of wind damage in summer called mesoscale convective systems (MCS).

Occasionally, an extreme version of an MCS called a derecho will develop. A derecho affects a widespread area hundreds of miles long with severe wind damage. Derechos are an infrequent event overall, but they most commonly occur from parts of the Southern Plains into the upper and mid-Mississippi Valley and the Ohio Valley.

(Source: NOAA's Storm Prediction Center)

Derechos can down numerous trees and lead to major power outages for days in the middle of summer. An extreme example occurred on June 29, 2012, when a derecho spread more than 600 severe thunderstorm wind reports from the Ohio Valley into the mid-Atlantic region. It was dubbed a "superderecho" by some because of how widespread the impacts were.

These widespread wind damage events most commonly occur from May through July.

In the South, daytime heating of the warm, humid air leads to isolated or scattered pop-up thunderstorm development most days. The Desert Southwest gets into the mix in July as annual monsoon moisture makes its way into the region, causing thunderstorms to form more frequently.

Any of those thunderstorms can produce a downburst that causes wind damage in a small area on a given day.

You can see in the map below how widespread damaging wind reports can be in summer because of all the atmospheric factors we've mentioned. Each blue dot represents one of more than 3,700 severe thunderstorm wind or damage reports in June 2019.

Blue dots show reports of severe thunderstorm winds or damage in June 2019.
(NOAA's Storm Prediction Center)

Although you should always be alert for damaging thunderstorms year-round, the summer months can be particularly dangerous with more people outdoors and in harm's way when it's warmer.

Severe thunderstorm winds in the United States claimed 36 lives in 2020 and 38 lives in 2019 , according to NOAA. Both 2018 and 2016 had more deaths from severe thunderstorm winds than tornadoes.

Be sure to have a way to get real-time weather alerts, and don't ignore severe thunderstorm warnings when they are issued.

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