(NEW YORK) — Cities across the heartland are expected on Monday to see temperatures close to 100 degrees, with the heat index in some locations reaching to 110.

More than 60 million Americans across 21 states are under heat alerts coast to coast.

The heat index is expected to soar between 100 and 110 in locations from South Dakota to Florida.

Temperatures this week will remain very hot over the middle and southern parts of the US, but not necessarily record-breaking.

The greatest heat risk this week will be in Oklahoma, where each day Oklahoma City is under extreme heat risk — a four out of four on the heat risk scale — due to their combined hot afternoons and very warm nights which won’t provide relief.

In South Dakota and Iowa, where there has been historic and catastrophic flooding, temperatures on Monday are expected to reach the 90s. Heat indices could reach up to 110 and a heat advisory has been issued.

Omaha, Nebraska; Kansas City, Missouri; Oklahoma City and Little Rock, Arkansas, are all forecast to reach around 100 degrees on Monday with heat indices up to between 105 and 110.

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