Heat advisory runs through Thursday; Spare the Air alert and red flag warning add to the risk
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Overview
Updated 1 hour agoThe heat advisory covering the Bay Area and Central Coast runs through Thursday at 10 p.m., with inland highs expected to hit 105°F. A Spare the Air alert for Wednesday warns of unhealthy smog, and a red flag warning for fire risk is in effect overnight.
San Francisco stays cooler, topping out in the mid-80s, but overnight lows in the 70s leave little relief. Alameda County opened cooling centers. The advisory comes two days after the anniversary of the 2017 Labor Day heat wave that killed six people.
Why it matters
Inland Bay Area highs near 105°F with warm nights threaten a region where many homes lack air conditioning.
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People Involved
Organizations Involved
Federal agency that issues weather forecasts, warnings, and advisories for the Bay Area and Central Coast.
City agency coordinating cooling centers, public outreach, and interdepartmental response.
Bay Area public media outlet that published the emergency alert and local context.
Timeline
September 2017 September 2026
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Heat advisory expires
Today WarningAdvisory lifts at 10 p.m. as a sea breeze sets in; coastal flood advisory active overnight.
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Peak heat day
WeatherWednesday is the hottest day, with inland highs near 105°F and limited overnight relief.
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Spare the Air alert issued for Wednesday
Air QualityBay Area Air District issues Spare the Air alert as ozone reaches unhealthy levels in the Eastern Zone and Santa Clara Valley.
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Red flag warning issued for Bay Area hills
FireNational Weather Service issues red flag warning from 11 p.m. Wednesday to 9 a.m. Thursday for critical fire weather. Possible power shutoffs.
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Coastal flood advisory for bayshore areas
FloodMinor coastal flooding expected along San Francisco, San Pablo, and Monterey bays, with tides up to 5.7 feet.
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Alameda County opens cooling centers
Public HealthAlameda County opens cooling centers at libraries, including extended hours at the Main Library.
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Heat advisory issued for the Bay Area
WarningNational Weather Service issues heat advisory Tuesday afternoon through late Thursday; inland highs expected near 105°F.
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City holds heat-preparedness hearing
PolicySan Francisco reviews heat plans after record warmth earlier in summer.
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Hottest July in over a decade
WeatherSan Francisco records its hottest July temperature in more than ten years.
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Record 90°F March day in San Francisco
WeatherCity sets a March record, signaling early-season heat.
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San Francisco hits 106°F, six die
EmergencyLabor Day heat wave kills six people and sends hundreds to hospitals.
Historical Context
3 moments from history that rhyme with this story — and how they unfolded.
European Heat Wave (2003)
A two-week heat wave killed roughly 15,000 people in France, most of them elderly city-dwellers in homes without air conditioning. The toll exposed how cities with low air-conditioning adoption are vulnerable to extreme heat.
France's health system was overwhelmed and a public inquiry followed.
The event pushed Paris and other European cities to build heat-warning systems and cooling plans for vulnerable households.
Like Paris in 2003, San Francisco has historically low air-conditioning penetration. Warm nights with little relief are the same mechanism that made the 2003 death toll so high.
San Francisco Labor Day Heat Wave (2017)
Temperatures hit 106°F in San Francisco on September 1, 2017. Six people died and hundreds were hospitalized as the city, unaccustomed to extreme heat, struggled to respond.
Hospitals saw hundreds of heat-related cases and the city scrambled to open relief sites mid-event.
The deaths drove San Francisco to build a formal heat-response network: cooling centers, interdepartmental coordination, and public outreach to vulnerable residents.
City officials cite the 2017 deaths as the reason for the coordinated response now in place. The anniversary fell the day before this advisory was issued.
Bay Area Exceptional Heat Wave (2024)
Abnormally hot October weather brought an exceptional heat wave across the Bay Area and inland valleys, with residents crowding Alameda Beach and cooling centers opening across the region.
Advisories stretched for days during what is normally a cool month.
It reminded local agencies that extreme heat can strike outside summer and keeps seasonal records in flux.
This week's September event follows the same pattern of late-season heat that has become more common in the region's recent record books.
