The National Weather Service has issued a heat advisory and an excessive heat warning for much of the Bay Area beginning Wednesday, with temperatures expected in the 90s and 100s.
The heat advisory is in effect through 9 p.m. Friday for the North Bay interior valleys, Santa Cruz Mountains and Santa Clara Valley, including San Jose and Hollister Valley. Temperatures are expected between 94 to 99 degrees.
The excessive heat warning -- which predicts temperatures between 98 to 108 -- is in effect from 11 a.m. Thursday through 9 p.m. Friday for many of the same areas, including in the North Bay mountains, East Bay valleys and mountains, Santa Lucia Mountains, Los Padres National Forest, mountains of San Benito County and interior Monterey County including Pinnacles National Park.
The forecast is that the hottest day of the week will be Thursday. While temperatures are expected to decrease slightly on Friday, it will still be hot.
The weather service shared this advice for the public: "Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances."
Cooling centers will be set up in Santa Clara County for those vulnerable to the heat.
The extreme heat across the state prompted Cal ISO to issue a Flex Alert from 5 p.m. to 10 p.m. Thursday, anticipating a strain on the power grid.
A Spare the Air alert also was issued for Thursday as air quality was expected to be poor, with excessive levels of smog.