(KRON) – The National Weather Service has extended the excessive heat warning for the third time for the Bay Area. The warning is now slated to end at 11 p.m. on Sunday. The NWS said weather conditions may be “dangerous.”  The Bay Area Air Quality Management District is also extending the Spare the Air Alert for smog through Sunday. This alert is issued when ozone pollution is forecast to reach unhealthy levels, according to the district. The San Francisco Department of Emergency Management said that heat waves can become more dangerous as time progresses. The department said, “Indoor temperatures can climb 10 degrees higher than outdoor temperatures and may last for 1-2 days following the heat event.” Photo: National Weather Service The department suggests drinking water, even when not thirsty, to stay cool. According to the DEM, alcohol, caffeine and sugary sports drinks are not ideal to drink in a heat wave. San Francisco Bay Area Forecast In a heat wave, heat exhaustion and heat strokes can occur. The DEM reminds residents that dizziness, excessive sweating, and nausea are all symptoms of heat exhaustion. A person having a heat stroke may have an altered mental state or loss of consciousness. In both cases, the DEM advises to call 911.   Here is a list of cooling centers in San Francisco:  Main Library – 100 Larkin Street – Air conditioning throughout the building  Chinatown/Him Mark Lai Branch Library – 1135 Powell Street – Air conditioning throughout the building  Glen Park Branch Library – 2825 Diamond Street – Air conditioning in the meeting room  Mission Bay Branch Library – 960 4th Street – Air conditioning throughout the building  North Beach Branch Library – 850 Columbus Avenue – Air conditioning in the meeting room  Potrero Hill Branch Library – 1616 20th Street – Air conditioning in the meeting room  The DEM urges residents to frequently check on family, friends and neighbors to remind them to keep cool and hydrated.