SAN FRANCISCO — If the sky looks hazy or you can smell smoke in San Francisco Wednesday, the most likely source is the prescribed burn underway on Angel Island.
Marin County's emergency portal confirmed that the burn began at 9 a.m. Wednesday, Sept. 23 and warned that smoke could be visible. A Wednesday post from Mayor Daniel Lurie's Instagram account said San Franciscans may notice hazy skies and the smell of smoke from the operation.
The same city update said Wednesday's controlled burn is expected to end at 4 p.m. and that crews plan to continue again Thursday, Sept. 24, between roughly 9 and 10 a.m. The timing remains subject to conditions on the island.
Why is it smoky in San Francisco today?
The smoke is coming from a planned prescribed burn at Angel Island State Park, not an uncontrolled wildfire on the island.
California State Parks is conducting the operation with CAL FIRE and the Marin County Fire Department. The agencies say the project is intended to reduce accumulated vegetation and fuel loads in the island's grasslands and coastal scrub.
Because Angel Island sits in the middle of San Francisco Bay, smoke can be visible from San Francisco and other communities around the Bay. Wind direction can also carry the smell of smoke into the city even when the burn itself is several miles away.
When will the Angel Island burn end today?
The city's Wednesday update says active burning is expected to end at 4 p.m. Sept. 23.
That does not mean the haze will disappear at 4 p.m. State Parks says smoke from Angel Island may remain visible for as long as three days after ignitions, depending on conditions.
The agency's broader burn notice says smoke may be visible from about 9 a.m. to 6 p.m. on burn days. The more specific 4 p.m. Wednesday end time came from the city's afternoon update.
Will there be more smoke Thursday?
Possibly. The city's update says crews expect to continue the controlled burn Thursday morning, with burning planned between roughly 9 and 10 a.m.
State Parks has said throughout the operation that burn timing can change because of wildfire activity, crew availability, weather, fuel moisture and predicted smoke movement. A morning burn can therefore be delayed, shortened or canceled if conditions are not suitable.
The Bay Area Air District's current prescribed-burn notice is effective Sept. 21–25 and covers 196 acres at Angel Island State Park.
Is this an Angel Island wildfire?
No. The current smoke is associated with a planned prescribed-fire operation.
State Parks began the larger project Sept. 8 but stopped after burning 62 acres. The original plan contemplated as many as 260 acres. The current phase is the continuation of that work, coordinated with the Bay Area Air Quality Management District.
Officials have specifically asked residents not to call 911 simply to report known smoke from the Angel Island prescribed burn so emergency dispatchers are not overwhelmed with duplicate calls. That guidance does not apply to a separate fire or an immediate threat to people or property.
What should you do if the smoke is bothering you?
If the smoke is irritating you, the city's Wednesday message advises staying indoors and checking on neighbors who may be affected. State Parks also advises limiting time in smoky areas.
For current conditions, check live particulate readings rather than judging air quality only by whether a plume is visible. Smoke impacts can vary sharply from one part of San Francisco to another as winds shift.
Is Angel Island open during the burn?
Yes. State Parks says Angel Island remains open during burn days, but some areas near the operation can close temporarily.
Possible closures include portions of the Ida Trail, Sunset Trail, fire roads and perimeter roads. Access to the summit of Mount Livermore may also be restricted on some burn days. Closures can continue for one to three days during and immediately after burning.
What to watch Thursday morning
For San Francisco residents, the key question Thursday will be wind and smoke movement once crews begin or decide whether to begin the next burn period.
If burning starts around the city's stated 9–10 a.m. window, haze or smoke smell could become noticeable again later in the morning. SF News Today will update this page if the burn window changes or officials report a significant air-quality impact in San Francisco.