* WHAT...Hot conditions with temperatures 10 to 20 degrees above normal during the day, with overnight lows also running 10 to 20 degrees above normal.
* WHERE...Bay Area and Central Coast.
* WHEN...Until 10 PM PDT Thursday.
* IMPACTS...This level of heat affects most individuals sensitive to heat, especially those without effective cooling and/or adequate hydration. Impacts possible in some health systems and in heat-sensitive industries. Hot conditions can cause heat illnesses.