Temperatures along the Peninsula could hit the upper 90s to low 100s on Wednesday and Thursday, Sept. 9–10, as a heat wave rolls through the Bay Area.
The National Weather Service issued a Heat Advisory covering the Bay Area and Central Coast from 10 a.m. Wednesday through 10 p.m. Thursday. The agency's Monday, Sept. 7, advisory described conditions 10 to 20 degrees above normal.
The NWS Bay Area office's Sept. 7 post on X specified interior highs of 90°F to 105°F, with coastal highs in the mid-70s to low-90s.
The San Francisco Chronicle reported that the Highway 101 and Interstate 280 corridor along the Peninsula could see upper 90s to low 100s during the advisory period. The heat wave is linked to remnants of Hurricane Marie disrupting the Bay Area's typical cooling sea breeze, according to the Chronicle.
Overnight lows will stay in the 70s and 80s in the hills, the weather service said. Chronicle meteorologist Anthony Edwards wrote that Wednesday night "will be brutally warm for people without air conditioning," with lows possibly not dropping below 70°F in interior South Bay valleys.
How to stay safe
The weather service urged residents to stay hydrated, wear lightweight and loose-fitting clothing, and limit strenuous outdoor activity to early morning or evening hours. The agency also warned that car interiors can reach lethal temperatures within minutes and that children and pets should never be left in unattended vehicles.
The City of Palo Alto advises avoiding outdoor and strenuous activities between 10 a.m. and 4 p.m. and using a buddy system when exercising in excessive heat.
The city operates a Community Respite Center at 250 Hamilton Ave. with listed daytime hours of 11 a.m. to 2 p.m. Residents should call (650) 329-2100 to confirm the center is open for this event.
Santa Clara County's Office of Emergency Management also maintains a list of cooling centers and urges residents to check on vulnerable neighbors without air conditioning.
When it ends
Relief is expected Thursday evening, when northwest winds are forecast to resume. Temperatures should return close to September averages by the weekend, with 60s at the coast, 70s along the bay shoreline and 80s inland, the Chronicle reported.
