More than 40 million Americans are under a severe weather alert beginning in the Plains and migrating east to the Mississippi River Valley as the most active storm month rages on.

These storms will likely bring hail, high winds and tornadoes to various states in the central Plains to start.

Severe storms hit Kansas City, Wichita, Oklahoma City, northern Texas

According to CNN, “a Level 3 out of 5 risk for severe storms is possible in western Oklahoma and northern Texas” and “a larger Level 2 of 5 risk surrounds that area and includes Kansas City, Wichita, and Oklahoma City.”

As the dangerous weather conditions ramp up into Monday evening and night, CNN advises people in areas with weather alerts to ensure they can receive notifications regarding severe weather. While people sleep, they will be unaware of oncoming tornadoes and dangerous weather and thus these storms become more deadly.

“Winds will be gusting up to 45 mph from western Nebraska down through the panhandle of Texas” in the lead up to the overnight storms, CNN reported.

Storms head east Tuesday, most heavily impacting South Dakota, Kansas

The storms will hit states further east on Tuesday, impacting the upper Mississippi River Valley, Texas, Arkansas and Louisiana, with the most severe weather likely to hit vast swaths of South Dakota and Kansas, per the Weather Channel.

“The most concentrated corridor for severe weather on Tuesday, especially for hail and tornadoes, is expected over southern Iowa and Missouri during the mid-afternoon and early evening,” per CNN.

Storms will likely lead to a greater flood risk in various impacted areas, Fox Weather reported.

The Weather Channel also reported possible severe thunderstorms in the Tennessee Valley and the Ohio Valley, moving into the east. It’s still too early for more specific forecasting, the body said.