Parts of the Midwest, including much of Illinois, could face a threat of violent, EF3 or stronger, tornadoes Monday as a multi-day severe weather outbreak enters what could be its most dangerous phase yet.

Widespread damaging winds, large hail and tornadoes also threaten nearly 40 million people across a broader zone from the Mississippi Valley into the lower Ohio Valley Monday.

The threat comes after days of severe weather have already carved a destructive path across parts of the Plains and South, producing more than 50 tornado reports since Thursday. These include a violent, preliminarily rated EF-4 tornado in Enid, Oklahoma, deadly tornadoes in North Texas and multiple Particularly Dangerous Situation tornado warnings Sunday evening.

A Level 3 of 5 risk for severe thunderstorms is in place Monday from parts of the middle Mississippi Valley into the lower Ohio Valley, including nearly all of Illinois and portions of Missouri, western Indiana, western Kentucky and northwestern Tennessee.

Some of these same areas have already been hit by severe storms in recent days. Monday could bring an initial round of supercells followed by a second round that may organize into a squall line later in the day.

Monday’s supercells may be capable of producing a few potentially violent EF-3 or stronger tornadoes and hail up to baseball size or larger. As storms evolve through the evening, the line could produce widespread damaging winds, though embedded circulations could continue to pose a tornado risk.

The corridor from central and southern Missouri into central Illinois may hold the most favorable environment for the strongest storms, though the precise location of the greatest tornado potential could depend in part on how morning thunderstorms shape the atmosphere ahead of the afternoon round.

The severe system pushes east Tuesday, with a somewhat lower, but still significant, Level 2 of 5 risk of severe thunderstorms from the southern Plains through the Mid-South and into the lower Ohio Valley.

A violent tornado tore through Enid, Oklahoma, Thursday evening, triggering a rare tornado emergency and causing EF-4 damage in parts of the city, with some areas flattened.

The Enid tornado, with winds estimated at 170 to 175 mph, was the strongest in the US since June 2025. At least 10 people were injured and about 40 homes were damaged, though officials said no deaths were reported.

Deadly tornadoes struck North Texas Saturday, including an EF-2 tornado near Runaway Bay, about 80 miles northwest of Dallas. At least two people were killed and homes and infrastructure were damaged, displacing dozens of residents and expanding the toll of the multi-day severe weather outbreak.