Relentless heat continues to scorch San Francisco Bay Area; excessive heat warning extended

The excessive heat scorching the Bay Area will last longer than originally forecast, with dangerously hot weather and fire concerns persisting through the weekend.

Early Wednesday morning, the National Weather Service extended an Excessive Heat Warning for most of the Bay Area and the Central Coast, warning of dangerously hot conditions with forecast temperatures up to 94 degrees in San Francisco and 113 degrees in elevated inland locations.

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The warning is now in effect until 11 p.m. Thursday in the North Bay coastal ranges and interior valleys, San Francisco Bay shoreline, East Bay interior, Santa Clara County, Santa Cruz Mountains and interior Monterey County. Originally the warning was set to expire on Wednesday night.

A strong high-pressure system was creating a heat dome over the region, compressing the typical marine layer and its cooling relief to near sea level, the Weather Service said. Most inland locations including in the hills and mountains Wednesday night were expected to remain warm or very warm overnight.

In addition, the Weather Service said elevated fire weather concerns will persist through the upcoming weekend, prompting a Red Flag Warning for portions of the Central Coast. Dry fuels, hot temperatures, and low humidity will combine to create and mix of near-critical to critical fire weather conditions, the Weather Service said in its daily area forecast discussion.

"The one factor that is in our favor are the winds. Generally speaking the winds are not overly strong," the summary said. "That being said, there is still periods of offshore flow forecast for the Central Coast through Thursday evening."

By early Wednesday evening, a few heat records were broken or matched across the Bay Area, according to the National Weather Service. 

In Marin County, San Rafael reached temperatures of 106 degrees, tying a previous record of 106 in 1980. 

Napa reached 103 degrees, beating out the record of 102 degrees in 1980, according to the weather service. 

San Jose hit 106 degrees, surpassing the previous record of 96 degrees in 1980 and 2012. 

The weather service cautioned that these readings are preliminary and official data will be had from the National Centers for Environmental Information.

The continued hot weather and weak winds also prompted the Bay Area Air Quality Management District to issue a fourth straight Spare the Air alert because of unhealthy smog levels.

Several October 1 high-temperature records were tied or set on Tuesday across the Bay Area. The record-breaking or near-record-breaking hot weather was expected to continue, possibly into the weekend, the Weather Service said.

In:
• National Weather Service
• Heat Wave