San Mateo County remains under a heat advisory through 10 p.m. Thursday, Oct. 8, as unusually warm October weather continues across the Bay Area.

The National Weather Service extended the advisory for interior portions of the Bay Area and Central Coast. Temperatures could reach the 90s in bayside parts of San Mateo County, while some inland Bay Area communities could reach triple digits, according to Local News Matters. Coastal areas are expected to cool to the high 70s after hitting the mid-80s over the weekend.

The advisory originally covered the weekend but has since been extended through Thursday for interior communities.

The Bay Area Air Quality Management District (BAAQMD) extended a Spare the Air Alert for ozone through Tuesday, Oct. 6. The alert warns of unhealthy ozone levels for sensitive groups. Residents are asked to limit driving on alert days.

The Air District's current forecast lists the Coast and Central Bay zone, which includes San Mateo, at an AQI of 97 Monday and 80 Tuesday, both in the moderate range. Higher ozone levels are forecast in other parts of the Bay Area, including the South Central Bay and Santa Clara Valley. The district advises outdoor exercise during Spare the Air alerts only in the early morning, when ozone concentrations are lower.

A high-pressure ridge over the western United States is driving the unusual October warmth, with temperatures in parts of the region running 15 to 25 degrees above normal, SFGate reported. NWS Bay Area meteorologist Dial Hoang told SFGate on Sunday, Oct. 4, that most inland areas would see daytime highs in the mid-90s through Wednesday, with some cities reaching 102 to 104 degrees.

"This is going to be very hazardous heat for a lot of people, especially in inland areas," Hoang said.

The National Weather Service advises residents to stay hydrated, shift outdoor activities to cooler parts of the day and never leave people or pets in unattended vehicles.

Residents can check daily air quality forecasts and sign up for email alerts at the Spare the Air website or call the BAAQMD's 24-hour line at 1-800-HELP AIR.