It started as a line of storms over Iowa late Wednesday afternoon. By the time it ran out of steam, it had chewed through five states, snapped utility poles like toothpicks, and left more than half a million homes and businesses sitting in the dark.
The June 10 windstorm was not your average thunderstorm. Forecasters called it a derecho, and it dragged hurricane-force winds across a 350-mile stretch of the Midwest. The storm started in Iowa on Wednesday, June 10, before blasting through Illinois, Wisconsin, Michigan, and Indiana. Trees and power lines went down everywhere it passed. Here is what happened, why it hit so hard, and the mess it left behind.
What a Derecho Actually Is
Most people have never heard the word, so here is the short version. A derecho is a long-lived windstorm that stretches at least 250 miles long and 60 miles wide. This one cleared that bar with room to spare. The damage formed a nearly continuous swath from eastern Iowa across northern Illinois, southern Wisconsin, and into northern Indiana.
One Chicago meteorologist said he had no qualms about calling it a derecho, pointing to the unbroken line of wreckage and the several spots where winds reached hurricane strength. The fuel behind all of it was simple weather chemistry: cool air rolling down from Canada slammed into warm, humid air from the South. That clash set off a storm line that just kept marching east, feeding on the heat and humidity in front of it.
Oshkosh Clocked a 94 MPH Gust
Wind gusts topped 80 mph across Illinois and Wisconsin, and the strongest reading of the day came out of Oshkosh, Wisconsin, where instruments caught a 94 mph gust. For comparison, that is firmly in Category 1 hurricane territory, just sitting over a Midwestern town. NOAA’s Storm Prediction Center logged more than 520 reports of intense wind, and a lot of those reports came with trees and poles on the ground.
The damage piled up fast. Strong winds tore part of the roof off an apartment building in the Chicago area, forcing people out of their homes. Barns collapsed in Wisconsin and buildings were crushed in rural northern Missouri. In the South Loop, gusts shattered at least 20 windows on the face of a high-rise on North Michigan Avenue. A property manager there called it really crazy and said they had never seen anything like it. Joliet and Elgin took some of the worst of it, with downed trees blocking roads and tangled wires across town.
Half a Million Customers in the Dark
At the peak of Wednesday’s storms, more than 500,000 customers had no electricity. By Thursday morning that number sat around 390,000, then slowly dropped to over 300,000 by the afternoon as crews chipped away at the damage. The catch is that progress was slow, because the storm did not just trip a few breakers. It snapped poles and ripped down wires, which is the kind of repair that takes days, not hours.
Illinois was the worst-hit state by far. Nearly 226,000 Illinois outages were reported early Thursday, with roughly 150,000 of those in Cook County alone. Michigan added another 85,000 customers without power. Central Illinois got hammered too, with Marshall County losing close to 40% of its customers. Commonwealth Edison, which serves northern Illinois, said more than 100 crews were working around the clock to put the grid back together.
More Than 1,000 Chicago Flights Grounded
If you were flying anywhere near Chicago on Wednesday, you felt this storm. Both O’Hare International and Midway International temporarily put all flights on hold during the evening as the storms rolled through. By the end of the night, more than 1,000 flights in and out of Chicago had been delayed or canceled.
The FAA put a ground delay program in place at O’Hare, and arriving and departing flights faced an average delay of 159 minutes. That is nearly two hours and forty minutes past schedule. United and American both run hubs out of O’Hare, so hundreds of their flights fell behind. Because O’Hare touches so much of the national air traffic system, the delays rippled out and gummed up connections far from the Midwest. Nearly 400 flights were canceled at O’Hare by 7 p.m. Wednesday, with another 200-plus canceled by midday Thursday. The good news: by Thursday morning, the national picture had mostly reset, with only about two dozen cancellations.
Tornadoes and One Death in Des Moines
The wind was the headline, but it was not the only threat. The National Weather Service received more than a dozen tornado reports Wednesday across northern Missouri, Iowa, Kansas, and Illinois. Several of those twisters struck rural areas as the larger storm system swept east.
The storm also turned deadly. In Des Moines, Iowa, a 54-year-old man died after being struck by a tree at a homeless encampment in a city park. Police said the tree broke apart and fell during the strong storms. He was found critically injured Thursday morning and died at the scene. It was the only fatality reported across the whole outbreak, which says something about how lucky a lot of people got given the scale of the damage.
Thursday Brought Round Two
As if one derecho was not enough, the same region got loaded up again. On Thursday morning, NOAA bumped the severe weather threat for northern Illinois and nearby areas up to a Level 4 out of 5, a rare Moderate Risk designation. Forecasters warned of widespread damaging winds, large hail, and tornadoes strong enough to reach EF3. The threat came in two rounds, one in the morning and a stronger one in the late afternoon and evening.
Some of those warnings turned real. A Tornado Emergency was issued for Marshall County, Illinois, covering the communities of La Rose, Toluca, and Wenona, along with a stretch of Interstate 39. City officials in Streator, Illinois, later confirmed a tornado touched down Thursday afternoon, with no deaths reported as crews assessed the damage. Zooming out, the larger weather setup stretched a storm corridor thousands of miles from the Central Plains into the Northeast, putting roughly 154 million Americans somewhere in the path of severe weather or flooding.
When the Lights Come Back
The hard truth for anyone still without power is that this kind of repair takes time. Snapped poles, downed wires, and trees draped over lines have to be cleared and rebuilt piece by piece, and Thursday’s second round of storms slowed crews down even more in spots they had already cleared. Utilities had hundreds of workers in the field, but the volume of damage made it a multi-day job.
The break finally came at the end of the week. By Friday, the Midwest was forecast to dry out and calm down, with highs near 80 and lows in the mid-60s. While the Midwest cleaned up, the East Coast had its own problem on the way, with high heat and heavy humidity pushing the feel-like temperature toward 100 degrees from the mid-Atlantic into the Northeast. For a storm that lasted a single afternoon, the June 10 derecho left a footprint that took the better part of a week to clean up.