A mid-summer heat wave currently affecting much of the southern and western U.S. will gradually expand, first reaching the northern Plains. 

Late in the weekend and early next week, temperatures will top 100°F as far north as Montana and the Dakotas.  In the western Corn Belt, widespread high temperatures ranging from 95 to 100°F should occur early next week. 

As the heat shifts eastward, slightly cooler air will begin to overspread the Northwest. 

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