NOAA Rates March 13–17 Blizzard ‘Extreme’ as Storm Iona Paralyzes Travel Across U.S. and Canada

Airports dark, roads closed

The departure boards at Minneapolis–St. Paul International Airport glowed red on a Sunday afternoon in mid-March, a wall of cancellations where spring break flights should have been. Outside, snow blown by 40 mph gusts swirled across empty runways. Inside, stranded travelers stretched out on the floor beneath a familiar ceiling announcement: their flights were not going anywhere.

By the time the storm system unofficially dubbed Winter Storm Iona moved off the North American coast on March 17, it had buried parts of the High Plains and Upper Midwest under more than four feet of snow, spawned dozens of tornadoes in the South and East, and knocked out power to well over a million people in the United States and Canada.

NOAA issues rare Category 5 designation

The mid-March storm—known in official bulletins as the March 13–17, 2026 North American blizzard—has been classified as a Category 5 (“Extreme”) storm on the National Oceanic and Atmospheric Administration’s Regional Snowfall Index, the highest level on that scale and the first such designation for a U.S. winter storm since 2016.

At its peak, the system produced blizzard conditions from Nebraska to northern Michigan, shut down highways and major airports, and left at least three people dead in winter-weather incidents.

Meteorologists and emergency managers said the storm capped a punishing winter that had already seen two major, deadly systems and exposed how vulnerable transportation networks and electric grids remain to late-season extremes.

“This was a powerful, rapidly intensifying surface low that produced a widespread area of significant snowfall,” the National Weather Service office in the Twin Cities wrote in its post-storm event summary.

From atmospheric river to “Colorado low”

The storm’s life cycle began over the Pacific. On March 12, an atmospheric river carrying moisture from the Pacific Ocean collided with Arctic air spilling south from Canada, dumping heavy snow in the mountains of Washington, Oregon, Idaho and Montana. As that disturbance moved east and descended the Rockies, it organized into a classic Colorado low on March 14, then rapidly strengthened.

By the early hours of March 15, the Weather Prediction Center was issuing national storm summaries as the low tracked across the central Plains toward the Upper Midwest. The storm tapped moisture from both the Pacific and the Gulf of Mexico, creating a broad shield of heavy snowfall on its cold side and a volatile warm sector to the south and east.

Blizzard conditions across the Upper Midwest

Blizzard warnings stretched across parts of the Dakotas, Nebraska, Minnesota, Wisconsin and northern Michigan. The Weather Service defines a blizzard as at least three hours of frequent or sustained winds of 35 mph or higher, with falling or blowing snow reducing visibility to a quarter-mile or less.

Those criteria were met over a wide area.

In Minnesota and Wisconsin, forecasters reported widespread totals of 10 to more than 20 inches, with deeper bands across central and northern counties. Minneapolis–St. Paul International Airport recorded 8.9 inches, its largest snowstorm of the 2025–26 season.

In northern Michigan, localized totals were dramatically higher: near the community of Round Lake, an unofficial measurement reached roughly 52 inches (132 centimeters) of snow.

Green Bay, Wisconsin, logged about 14.8 inches on March 15—its snowiest calendar day in 137 years of records, according to local tallies.

Travel quickly became treacherous. The Weather Service office in the Twin Cities noted that by the morning of March 15, “all roads had become at least partially if not fully covered in snow” across southern Minnesota and much of Wisconsin. Along Interstate 94 between Eau Claire and Osseo, Wisconsin, the agency said “several vehicles became stranded” in whiteout conditions.

Tornadoes, dust and coastal winds

Farther south, where the storm’s cold front sliced into warm, humid air, the same system unleashed a two-day severe weather outbreak. The Storm Prediction Center confirmed 51 tornadoes between March 15 and 16, most rated EF0 or EF1. The strongest, with estimated winds up to 110 mph, struck near Caneyville, Kentucky.

Straight-line wind gusts reached 77 mph near Minturn, Arkansas, and hailstones as large as 2.5 inches in diameter were reported near Cushing, Texas.

As the front swept across the southern Plains, it also kicked up a wall of dust in parts of West Texas, briefly reducing visibility to near zero and contributing to at least one multi-vehicle pileup captured by highway cameras and weather satellites.

To the east, the maturing low turned into a powerful windstorm. Gusts exceeding 70 and 80 mph were recorded at elevated sites in New England, including an 81 mph gust at Blue Hill Observatory in Massachusetts. Heavy rain and strong onshore winds triggered coastal flooding and tree damage from New Jersey to Maine.

Thousands of flights canceled during spring break

With snow, ice and high winds hitting different regions at once, the storm upended travel on land and in the air.

Flight-tracking data showed that more than 5,000 flights were canceled across the United States between March 15 and the morning of March 16, with one outlet citing more than 5,600 cancellations and delays in less than 36 hours. On Sunday, March 15, airlines scrubbed roughly three-quarters of departures from Minneapolis–St. Paul and more than a quarter of flights at Chicago O’Hare International Airport.

As the system moved east, hundreds of additional flights were canceled at New York’s LaGuardia and John F. Kennedy airports, Newark Liberty International and Boston Logan.

The timing was particularly disruptive: the storm hit during one of the busiest spring break travel weekends of the year, stranding families and college students at hubs across the Midwest and Northeast. Major U.S. carriers, including Delta Air Lines, American Airlines and Southwest Airlines, issued travel waivers allowing customers to change itineraries without fees, but rebooking options were limited as routes filled and aircraft and crews fell out of position.

Outages in the U.S. and Canada

On the ground, the storm tested power grids across two countries.

In the United States, utilities reported more than 500,000 customers without electricity at various points, concentrated in the Upper Midwest and New England. In Massachusetts alone, the state emergency agency cited a peak of about 65,000 homes and businesses without power early on March 17.

In Canada, impacts were even more severe in some provinces. Environment and Climate Change Canada issued winter storm warnings across large parts of Ontario and Quebec as the system moved north. The city of Sudbury, Ontario, declared a “significant weather event” under provincial law, alerting residents that normal standards for road maintenance may not be met during a major storm.

Sudbury recorded 42.1 centimeters (16.6 inches) of snow, its heaviest March snowfall since 1959. Sault Ste. Marie reported 55 centimeters. Two inflatable sports domes in Sudbury collapsed under the weight of heavy, wet snow, a visible example of the strain on local infrastructure.

In Quebec, wind gusts of 90 to 120 kilometers per hour (55 to 75 mph) battered parts of the province. Hydro-Québec reported that about 315,000 customers were without power on the morning of March 17; over the course of the event, more than one million people experienced outages, the utility said.

The Maritimes also felt the storm’s reach. Heavy rain, strong winds and a rapid temperature drop led to power failures for more than 15,000 customers across Nova Scotia, New Brunswick and Prince Edward Island, and prompted bridge and ferry closures that briefly cut some interprovincial links.

Deaths, delays and economic ripple effects

At least three deaths were directly tied to the winter-weather side of the storm. In Newtown Square, Pennsylvania, a man was killed when a tree fell while he was clearing another downed tree after high winds. In Mount Pleasant, New York, authorities said a driver died after swerving to avoid a fallen tree and crashing. Other injuries were reported in traffic accidents and in the southern severe weather outbreak.

The storm also rippled through the economy. Trucking routes that move grain, fertilizer and manufactured goods across the northern tier were shut down or slowed, especially along Interstates 94 and 35. Rail operators rerouted or delayed freight trains through the Upper Midwest and cross-border corridors into Ontario.

Agriculture analysts noted that while the deep, late-season snowpack would delay early spring fieldwork in parts of Minnesota, Wisconsin and Michigan, it could improve soil moisture and streamflows heading into planting.

A winter of repeated extremes—and questions about risk

The March blizzard did not arrive in isolation. It followed a deadly late-January winter storm blamed for at least 174 deaths across the United States and a February blizzard that killed about 30 people, cut power to more than 600,000 customers and triggered more than 9,000 flight cancellations. For snowplow crews, utility lineworkers and emergency managers, Iona was the third major deployment in less than two months.

The string of severe winter storms is prompting questions about how climate change is reshaping cold-season risks. A warmer atmosphere can hold more moisture, which can fuel heavier precipitation—including snow—when cold air is present. Some researchers have also pointed to larger temperature contrasts and shifts in the jet stream that can intensify extratropical cyclones like Iona.

Scientists caution that it will take time for formal studies to attribute what role, if any, human-caused warming played in this particular storm. Still, they say, the March blizzard fits a broader pattern of heavier winter precipitation in the northern United States and more frequent episodes of “weather whiplash”—heat, floods, snow and severe storms in rapid succession.

Even as communities in the Midwest and eastern Canada finish clearing debris and repairing damaged lines, policymakers and utilities are digesting what the storm revealed. Proposals to bury more power lines in wooded suburbs, strengthen design standards for roofs and temporary structures, and expand mutual-aid agreements among utilities are likely to get renewed scrutiny.

For many residents, though, the lessons are more immediate. In neighborhoods from Duluth to Drummondville, snowbanks still tower over sidewalks—reminders of a March week when winter reclaimed the calendar. After a season of repeated “historic” storms, there is a growing sense that what used to be considered exceptional may no longer be rare, and that the systems built for a gentler climate are being forced to catch up.