Many spots across the northern tier of the nation will see a wet Thursday, while the most intense heat wave of the summer roasts most of the South.
Northern tier: Drenching rain and thunderstorms will soak areas from the northern Rockies, to the northern Plains, to the Great Lakes to the Northeast. The heaviest rain should be in the upper Midwest and Ohio Valley.
South: Some scattered showers and thunderstorms are possible in Arizona and Florida. The rest of the southern tier from the Southwest to the Deep South should be very hot and dry. Many spots will soar into the upper 90s to low 100s.
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Weather history for Aug. 21: In 1977, a killer tornado lashed Lake Matoon, Ill., leaving six people dead. In 1984, a vicious hailstorm hit the Colorado State Fair in Pueblo, injuring nine people.
In 2003, Topeka, Kan., had a record high temperature of 107 degrees.