High weekend temperatures prompt excessive heat warning Bill Regan posted this photo on Dave Hovde's Facebook page. Bill Regan posted this photo on Dave Hovde's Facebook page. and last updated 2021-07-07 16:52:38-04 Parts of the Central Coast will experience dangerously hot temperatures this weekend. The National Weather Service has issued an excessive heat warning in effect from 10 AM Friday to 9 PM Monday for San Luis Obispo County Interior Valleys, Cuyama Valley and the San Luis Obispo County Mountains. Expect dangerously hot conditions with temperatures of up to 110 degrees. The extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities.