Temperatures from the mid 90s to lower 100s in the valley are expected, and a heat advisory will be in effect from noon to 8 p.m. Friday and Saturday, according to the Weather Service.
In addition to Santa Clara County, affected areas include San Francisco, Santa Cruz, San Mateo, Marin, Monterey, Contra Costa, Napa, Sonoma and Alameda counties.
Elderly or heat-sensitive residents are advised drink plenty of water and seek cooler locations.
