TOLEDO, Ohio (AP) — Extreme heat alerts are in effect for tens of millions of people in the United States as cities including Chicago break heat records. Warnings stretched from Iowa to Ohio and even into the upper reaches of Michigan on Tuesday. The dangerous heat wave is expected to linger until at least Friday. The mid-Atlantic and New England are likely to see highs in the 90s as the week progresses. Excessive humidity will make it feel even more oppressive. The U.S. last year saw the most heat waves since 1936. Officials are warning people to drink plenty of water and stay indoors.