A partial cloud cover and scattered showers provided temporary relief from a searing heat wave to parts of the Southeast. But the hot, humid weather spread to the Midwest, prompting officials in St. Louis to declare a heat warning. Temperatures dipped into the 90s in Charleston, S.C., Charlotte, N.C., Birmingham, Ala., and Jackson, Miss. The stagnant front has been blamed for at least 14 deaths in the Southeast. The temperature in St. Louis was near 100, and most of Illinois had 90-degree weather.