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Bay Area faces three-day heat wave with inland highs near 105

Bay Area faces three-day heat wave with inland highs near 105

Built World San Francisco, CA local

Heat advisory runs through Thursday; Spare the Air alert and red flag warning add to the risk

September 10th, 2026: Heat advisory expires

Overview

Updated Sep 10

The 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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Key Indicators

105°F
Peak inland daytime high
Expected Wednesday, the hottest day of the event.
70s°F overnight
Overnight lows
Mid-60s to low-70s overnight means little recovery from daytime heat.
6
Deaths in 2017 Labor Day heat wave
Benchmark that drove San Francisco's heat-preparedness overhaul.

Voices

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People Involved

Dial Hoang
Dial Hoang
Meteorologist, National Weather Service Bay Area
Briefing the public on this heat event
 Jackie Thornhill
Jackie Thornhill
Spokesperson, San Francisco Department of Emergency Management
Coordinating the city's heat response
 Rick Canepa
Rick Canepa
Meteorologist, National Weather Service Bay Area
Authoring the daily forecast discussion

Organizations Involved

National Weather Service
National Weather Service
Federal agency
Issuer of the heat advisory

Federal agency that issues weather forecasts, warnings, and advisories for the Bay Area and Central Coast.
San Francisco Department of Emergency Management (DEM)
San Francisco Department of Emergency Management (DEM)
City agency
Coordinating the city's heat response

City agency coordinating cooling centers, public outreach, and interdepartmental response.
KQED
KQED
Public media organization
Reporting the advisory

Bay Area public media outlet that published the emergency alert and local context.

Timeline

September 2017 September 2026

11 events Latest: September 10th, 2026 · 2 months ago Showing 8 of 11
Tap a bar to jump to that date

  1. Heat advisory expires

    Latest Warning

    Advisory lifts at 10 p.m. as a sea breeze sets in; coastal flood advisory active overnight.

  2. Peak heat day

    Weather

    Wednesday is the hottest day, with inland highs near 105°F and limited overnight relief.

  3. Spare the Air alert issued for Wednesday

    Air Quality

    Bay Area Air District issues Spare the Air alert as ozone reaches unhealthy levels in the Eastern Zone and Santa Clara Valley.

  4. Red flag warning issued for Bay Area hills

    Fire

    National Weather Service issues red flag warning from 11 p.m. Wednesday to 9 a.m. Thursday for critical fire weather. Possible power shutoffs.

  5. Coastal flood advisory for bayshore areas

    Flood

    Minor coastal flooding expected along San Francisco, San Pablo, and Monterey bays, with tides up to 5.7 feet.

  6. Alameda County opens cooling centers

    Public Health

    Alameda County opens cooling centers at libraries, including extended hours at the Main Library.

  7. Heat advisory issued for the Bay Area

    Warning

    National Weather Service issues heat advisory Tuesday afternoon through late Thursday; inland highs expected near 105°F.

  8. City holds heat-preparedness hearing

    Policy

    San Francisco reviews heat plans after record warmth earlier in summer.

  9. Hottest July in over a decade

    Weather

    San Francisco records its hottest July temperature in more than ten years.

  10. Record 90°F March day in San Francisco

    Weather

    City sets a March record, signaling early-season heat.

  11. San Francisco hits 106°F, six die

    Emergency

    Labor Day heat wave kills six people and sends hundreds to hospitals.

Scenarios

1

Heat advisory lifts with minimal health impact

Deadline passed (Sep 15, 2026)

Discussed by: National Weather Service forecast; Bay Area emergency managers

The advisory expires Thursday at 10 p.m. as a sea breeze returns, and Friday settles near average temperatures. If emergency room visits and mortality stay within normal ranges, the event registers as a well-managed heat wave — the outcome city agencies have aimed for since the 2017 deaths. This is the baseline expectation given the region's preparedness.

2

Warm nights push heat illness cases up

Deadline passed (Q3 2026)

Discussed by: NWS forecast discussion by Rick Canepa; local health officials

High dewpoints and humidity keep overnight lows in the 70s, slowing the body's recovery between hot days. Emergency rooms and public health agencies see elevated heat-related visits, particularly among elderly residents and outdoor workers. This mirrors the 2017 pattern, when hundreds ended up in hospitals, and would stress the city's cooling network.

3

Another heat event follows within days

Deadline passed (Sep 18, 2026)

Discussed by: AccuWeather forecast; NWS long-range outlook

A lingering high-pressure ridge could set up a second heat advisory within a week or two, extending stress on vulnerable residents and testing city cooling resources again. Forecasters currently see near-average temperatures through the weekend, so this is a tail risk rather than the base case.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

September 2017

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.

Then

Hospitals saw hundreds of heat-related cases and the city scrambled to open relief sites mid-event.

Now

The deaths drove San Francisco to build a formal heat-response network: cooling centers, interdepartmental coordination, and public outreach to vulnerable residents.

Why this matters now

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.

August 2003

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.

Then

France's health system was overwhelmed and a public inquiry followed.

Now

The event pushed Paris and other European cities to build heat-warning systems and cooling plans for vulnerable households.

Why this matters now

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.

October 2024

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.

Then

Advisories stretched for days during what is normally a cool month.

Now

It reminded local agencies that extreme heat can strike outside summer and keeps seasonal records in flux.

Why this matters now

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.

Sources

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KQED KQED ABC7 San Francisco National Weather Service CBS San Francisco Mountain View Voice KTVU FOX 2 The Daily Californian