Bay Area heat climbs into 90s, red flag warning issued

Temperatures climbed into the 90s across the San Francisco Bay Area Thursday, while the National Weather Service warned that widespread Moderate HeatRisk covered much of the region Thursday and Friday. The compound threat was most acute in the North Bay interior mountains, where the strongest winds and critically dry conditions created the highest fire-weather concern.

A Red Flag Warning remained in effect from 11 p.m. Wednesday through 9 a.m. Thursday for the North Bay interior mountains and East Bay hills, including parts of Alameda, Contra Costa, Lake, Napa, Sonoma and Solano counties. Forecasters said northwesterly winds could gust as high as 45 mph, a setup that increased the chance that a spark could spread quickly through dry vegetation.

The weather service said the heat risk extended beyond the fire zones into the rest of the Bay Area and the Central Coast. It warned that the conditions could trigger heat-related illness, especially among children, older adults and people who work or live outdoors, groups that are more exposed when temperatures rise and cooling access is limited.

Public safety messaging centered on the basics: drink water, take breaks in air conditioning or shade, shift strenuous outdoor work and recreation to cooler parts of the day, and never leave children or pets in vehicles. Forecasters also stressed that most wildfires are caused by humans, and urged residents not to create sparks through everyday activities.

The Bay Area’s red flag warning was the region’s first in nearly two years, according to ABC7, underscoring how unusual the combination of heat, wind and dry fuel had become. The same weather pattern was also being watched farther inland, where elevated fire danger stretched across northern California.

On top of the heat and fire threat, the National Weather Service also issued a Coastal Flood Advisory. It said as much as 1.5 feet of inundation above ground level was possible in some low-lying shoreline areas during high tide Wednesday night and Thursday night, adding another hazard for communities already dealing with soaring temperatures and dangerous wind.