A hot spell will bring warm temperatures Tuesday throughout San Diego County, with even hotter temperatures expected in the deserts in the next few days. A high pressure system moving in from Texas will bring a rise in temperatures through Wednesday in coastal and inland valley areas and through Thursday in the county mountains and deserts, according to the National Weather Service. The weather service issued an excessive heat warning that will last from 11 a.m. Wednesday through 9 p.m. Thursday for desert areas. A heat advisory will also be in effect during that same time period for the inland valleys, including El Cajon, Santee and Escondido.