COLUMBIA — The National Weather Service has issued a heat advisory for much of eastern South Carolina. The weather service says the warning about excessive heat will be in effect Monday from midday until early evening. Forecasters say heat index values as high as 110 degrees are possible because of temperatures in the mid- to upper-90s and high humidity. The advisory is in effect in Allendale, Berkeley, Colleton, Charleston, Dorchester, Florence, Georgetown, Hampton, Horry, Jasper, Marion and Williamsburg counties. read more