The National Weather Service has issued a heat advisory for San Francisco and the surrounding Bay Area as conditions for some of the warmest temperatures of the year align.
As anticipated in earlier forecasts, the advisory begins at 11 a.m. Thursday and continues through 11 p.m. Friday for parts of San Francisco and the Bay shoreline, as well as parts of Santa Clara County, including San Jose and the Santa Cruz mountains.
A heat advisory remains in effect for portions of San Francisco, San Mateo, Alameda, Contra Costa, Santa Clara, and Santa Cruz counties Thu-Fri.
— NWS Bay Area 🌉 (@NWSBayArea) October 5, 2023
Wednesday was a little warmer than expected and we've adjusted the forecast higher for the coming days. pic.twitter.com/3E9N52Q8e3
Drier, warmer air from the state's north and inland will sweep in an "offshore flow" pattern toward coastal areas, thanks to a high-pressure system's presence overhead. That pattern will send daytime temperatures soaring in neighborhoods south of Downtown, like the Mission, SoMa and the Bayview, and along the city's Interstate 280 corridor.
National Weather Service meteorologist Sarah McCorkle told The Standard that temperatures in the city could reach 90 degrees.
"It'll be a toasty day," McCorkle said. "If it comes to fruition, that'll be the hottest day thus far this year."
Friday will see similarly warm temperatures peaking in the high 80s before cooling off Saturday and returning to seasonal ranges Sunday.
During the advisory, McCorkle advised residents and visitors to take precautions while attending outdoor activities and events, including hydrating with water and taking shade breaks if needed.
HEAT ADVISORY
— SAN FRANCISCO FIRE DEPARTMENT MEDIA (@SFFDPIO) October 5, 2023
Today is going to be a hot one in the City!
Drink plenty of water, wear light clothes, wear sunscreen.
Avoid strenuous activities outside until later in the day as temps cool.
Don’t leave children or animals in parked cars.
Check on your neighbors and remember to… https://t.co/4dM6EveikW
Residents should consider visiting stores, malls, libraries or other venues with air conditioning. Pet owners should avoid walking animals on hot sidewalks and keep them out of parked vehicles, which are likely to heat up fast with exposure to the sun.
Health experts and emergency services warn that excessive exposure to heat can cause illnesses as serious as strokes, exhaustion and cramps—all issues exacerbated by a lack of access to fans, air conditioning or adequate cooling areas.
Wednesday saw highs of 86 in Downtown San Francisco and 90 at San Francisco International Airport, well above the normal respective temperatures of 71 and 74 degrees. Record temperatures for Thursday's date are 99 at the airport and 102 in Downtown, both reached in 1987.
Thursday's memorial for the late Sen. Dianne Feinstein at City Hall will no longer be open to the public, her office announced late Wednesday. Mourners who do show up can expect to be stuck behind a large security perimeter in the baking heat.
"It just wouldn't be an enjoyable experience," Feinstein spokesperson Adam Russell said.