Temperatures in the inland parts and higher elevations of the San Francisco and Monterey Bay areas will be much hotter than usual Tuesday and Wednesday, National Weather Service officials said.
A heat advisory is in effect until 9 p.m. Wednesday for higher elevations such as the North Bay mountains, mainly around Lake Berryessa, the East Bay hills and Santa Cruz Mountains.
Weather service officials may issue a heat advisory for inland locations in the two areas if forecasted temperatures rise slightly.
A heat advisory means dangerous temperatures are expected, potentially causing heat-related illnesses.
In inland areas and those at high elevations, temperatures are expected to reach 100 to 105 degrees with some areas approaching 110 degrees.
In Concord on Tuesday, De La Salle band members and football players had abbreviated practices in the sweltering heat as the school's athletic trainer closely monitored both groups.
"We have water coolers out here," trainer Doug Bauman said. "There's water on each field."
Band members took frequent breaks and moved much of their practice into the shade. The football team also made modifications.
"We won't have equipment on today," Bauman said. "Sometimes it's a matter of taking off equipment to allow bodies to cool a little better. Sometimes it's a matter of changing when (what time) practice is."
Meanwhile, weather service officials urge residents to look inside their cars before locking them to be sure no pets or children have been left behind.
Temperatures near the coast will be more seasonal and above-average elsewhere. While it may be cooler at the coast, visitors should check for any beach hazards that could make visiting beaches risky.
Weather service officials said prolonged exposure to high temperatures increases the chance that people, especially those with respiratory conditions, will suffer heat-related illnesses.
Also, pets and livestock may need extra care during the hot weather. The chance of wildfires is also higher, according to the weather service.
During the heat, residents and visitors are encouraged to drink enough fluids, stay in air conditioning, stay out of the sun and check on relatives and neighbors.
On Tuesday, several community centers in San Jose offered extended hours to help residents beat the heat.
The community centers, spread across the city, will all be open until 9 p.m. City officials said that the centers act as cooling centers when temperatures reach or exceed 97 degrees.
The locations are Bascom Community Center at 1000 S. Bascom Ave., Camden Community Center at 3369 Union Ave., Mayfair Community Center at 2039 Kammerer Ave., Roosevelt Community Center at 901 E. Santa Clara St. and the Seventrees Community Center at 3590 Cas Drive.
The city of San Ramon also released locations and hours for cooling centers this week:
Tuesday: San Ramon Community Center 8:30 am-9 pm; Alcosta Senior and Community Center 8:30 am-9 pm; Dougherty Station Community Center 8:30 am-5 pm; Dougherty Station Library noon-8 pm; San Ramon Library 10 am-8 pm.
Wednesday: San Ramon Community Center 8:30 am-9 pm; Alcosta Senior and Community Center 8:30 am-7 pm; Dougherty Station Community Center 8:30-5 pm; Dougherty Station Library noon-8 pm; San Ramon Library 10 am-8 pm.
Thursday: San Ramon Community Center 8:30 am-8 pm; Alcosta Senior and Community Center 8:30 am-9 pm; Dougherty Station Community Center 8:30 am-5:30 pm; Dougherty Station Library 10 am-8 pm; San Ramon Library 10 am-8 pm.
Friday: San Ramon Community Center 8:30 am-5 pm; Alcosta Senior and Community Center 8:30 am-7 pm; Dougherty Station Community Center 8:30 am-5 pm; Dougherty Station Library 10 am-5 pm; San Ramon Library 10 am-5 pm.
NBC Bay Area's Jodi Hernandez contributed to this report.