A significant heat wave is affecting large parts of California, prompting multiple advisories and warnings. The National Weather Service has issued heat advisories for the Bay Area, with temperatures reaching the upper 90s to lower 100s, even in typically cooler San Francisco. Southern California is facing triple-digit temperatures, with excessive heat warnings in place for areas like Riverside County and San Diego County, where temperatures are expected to hit 107 degrees. The heat is also exacerbating poor air quality, with ozone advisories issued for several Southern California counties. Residents are advised to stay hydrated, use air conditioning, and avoid outdoor activities during peak heat hours. Vulnerable populations, such as the elderly and those without adequate cooling, are particularly at risk.