Walnut Creek could approach 100 degrees Saturday as a ridge of high pressure pushes inland Bay Area readings 10 to 15 degrees above normal.

The National Weather Service extended its heat advisory Friday, Oct. 2, for the East Bay and other parts of the Bay Area and Central Coast. It takes effect at 11 a.m. Saturday, Oct. 3, and continues through 10 p.m. Monday, Oct. 5, according to the weather service.

Inland highs are forecast in the mid-90s to near 103, the NWS said. Walnut Creek specifically is expected to approach triple digits on Saturday, SFGATE reported, citing NWS meteorologist Roger Gass.

Overnight lows in the upper 60s to mid-70s at higher elevations will limit the body's ability to recover from daytime heat. That raises the risk.

The NWS warned that prolonged time outdoors, especially during physical activity, increases the chance of heat-related illness. The agency said anyone without effective cooling or adequate hydration is at risk, and that impacts are likely in some health systems and heat-sensitive infrastructure, according to the East Bay Times.

Gass told SFGATE the high-pressure system driving the heat is expected to remain in place through much of the week and into the following week.

The weather service advises residents to drink plenty of water, shift outdoor activities to cooler hours, take frequent breaks in air-conditioned spaces or shade, and never leave people or pets in unattended vehicles.

Contra Costa County's heat safety page lists cooling resources and health information. Residents who need transportation to a cooling location can call 211 or Mobility Matters at (925) 284-2207. The county also urges residents to sign up for emergency alerts through the Community Warning System at cwsalerts.com.