 It's a dangerously hot day across much of Maryland. The National Weather Service has an excessive heat warning in effect until this evening for central, northern and southern Maryland, as well as parts of western Maryland and the eastern shore. Heat index values could reach 110 degrees. An excessive heat watch is posted for Tuesday. The Weather Service advises drinking plenty of fluids, staying in an air-conditioned room, staying out of the sun and checking on relatives and neighbors.