The National Weather Service has issued a heat advisory in effect until 9 p.m. tonight for the San Francisco Bay Area. A ridge of high pressure combined with offshore winds will lead to temperatures above what are normally seen in the area, according to the National Weather Service. Temperatures are expected to be in the mid-80s to mid-90s on the coast and could reach 100 degrees in inland areas. Temperatures are expected to begin to cool over the weekend, but the National Weather Service is forecasting warm temperatures at least through Saturday. The advisory was issued just before 9 p.m. Thursday.