UPDATE FRIDAY: Northbound Highway 101 through Hospital Curve is scheduled to close tonight at 11 p.m. and remain fully closed until 6 a.m. Labor Day Monday, Sept. 7. Southbound 101 remains open.
Caltrans plans to close all northbound lanes of US-101 through Hospital Curve beginning at 11 p.m. Friday, Sept. 4. The freeway is scheduled to reopen by 6 a.m. Labor Day Monday. The agency’s Aug. 19 closure notice tells motorists to avoid the corridor and use I-280 northbound instead.
That puts the closure directly in the path of drivers coming from San Francisco International Airport, San Mateo County and the South Bay toward central San Francisco. It also means navigation apps will be redistributing a large volume of traffic onto a smaller set of freeway ramps and city streets during one of the busiest travel weekends of the year.
What time does Highway 101 close this Labor Day weekend?
| Closure | Starts | Scheduled reopening |
|---|---|---|
| Labor Day weekend | Friday, Sept. 4 at 11 p.m. | Monday, Sept. 7 by 6 a.m. |
| Second northbound weekend | Friday, Sept. 18 at 11 p.m. | Monday, Sept. 21 by 6 a.m. |
The Monday morning reopening is important. “Labor Day weekend closure” can sound as though the freeway remains closed through Monday evening. Under the current schedule, it does not.
That means someone returning to San Francisco Sunday afternoon or Sunday night should plan around the full closure. Someone driving into the city Monday afternoon for the Giants–Cardinals game should not encounter this particular shutdown if Caltrans finishes on schedule.
Driving from SFO, the Peninsula or South Bay into San Francisco
Coming from SFO toward San Francisco: the normal northbound 101 route through Hospital Curve will be interrupted. Drivers should make the I-280 decision early instead of reaching Cesar Chavez and then searching for a surface-street workaround.
Going from San Francisco toward SFO: southbound 101 remains open. That does not guarantee normal travel times — detour traffic can spill onto connecting roads — but the southbound freeway itself is not part of the Sept. 4–7 full closure.
Caltrans has published detour maps specifically for motorists travelling from SFO, the rental-car center, the Peninsula and South Bay. For airport trips with a fixed check-in or pickup time, extra margin is more useful than trying to predict a precise delay several days in advance.
Where exactly is the closure?
Caltrans’ Aug. 19 notice describes the northbound shutdown as between Cesar Chavez Street and 10th Street. A later Caltrans project update refers to the paving area as running toward 17th Street, while SFMTA uses the 7th Street exit as its practical northern reference in traffic guidance.
Those descriptions are not identical, and SF News Today is not treating them as though they are. For trip planning, the important point is that motorists cannot continue north through Hospital Curve into central San Francisco and should follow the posted closure and detour signs in the field.
What is the best detour?
Caltrans’ principal regional alternative is I-280 northbound, especially for travel toward downtown San Francisco or the Bay Bridge. SFMTA’s traffic advisory also identifies northbound Potrero as an alternative and says Parking Control Officers will be stationed at critical points on the detour network.
The earlier a driver switches to the appropriate route, the less likely they are to join a last-minute queue near the closure. A navigation app may identify a neighborhood shortcut that saves several minutes when few people use it; the calculation changes when thousands of phones are making the same recommendation.
Dogpatch has a separate street closure during the same weekend
The freeway work overlaps with an ISCOTT-approved closure for The Midway’s 2026 block-party dates. Marin Street between Illinois Street and its easterly terminus and Michigan Street between Cesar Chavez and Marin Street are approved to close from 4 p.m. Friday until 6 a.m. Monday, with local access allowed through specified approaches.
The Midway block-party events closure runs from 4 p.m. Friday, Sept. 4 until 6 a.m. Monday, Sept. 7.
That closure is not a Caltrans detour and should not be confused with one. Its significance is that another traffic-generating event begins near Cesar Chavez several hours before northbound 101 shuts Friday night. SF News Today’s Midway Labor Day weekend guide has the event schedule, street-closure details and transit options.
Would BART or Caltrain avoid the closure?
Rail avoids the closed freeway segment entirely. BART remains an obvious alternative between SFO and central San Francisco for trips that fit its schedule. Caltrain can also bring Peninsula and South Bay riders into 4th & King without using Highway 101.
Labor Day Monday itself uses holiday schedules, so riders should not assume an ordinary weekday timetable. Our Labor Day Muni, BART, Caltrain and parking guide explains the Monday service changes.
How bad could traffic get?
Caltrans is warning motorists to expect delays, but there is no responsible way to promise a specific extra travel time before the weekend begins. Congestion will depend on departure time, how quickly traffic redistributes toward I-280, event demand and any unrelated collisions or stalled vehicles.
The safest assumption is simply that the normal northbound 101 travel time into San Francisco will not apply. People with reservations, ticketed events or flights should treat the detour as a material part of the trip rather than an incidental construction zone.
Why is Caltrans closing the entire freeway?
The work is part of the Fab 4 Hospital Curve Rehabilitation Project, a multi-year reconstruction effort that began in 2025. Caltrans says crews will perform major pavement repairs and continuous reinforced-concrete paving while the roadway is unavailable, working around the clock during the closure window.
A full weekend gives crews a continuous work period that cannot easily be achieved through a series of short nighttime lane closures. Caltrans completed drainage work during an earlier August closure and is now moving into the major paving phase.
This is not the last Highway 101 closure
A second complete northbound shutdown is currently planned from 11 p.m. Friday, Sept. 18 through 6 a.m. Monday, Sept. 21.
SFMTA also says Caltrans contractors plan complete southbound closure weekends in October, with more detailed guidance expected as those dates approach.
The useful time to learn about the Labor Day closure is before traffic begins reorganizing itself Friday night. Drivers should check Caltrans QuickMap or 511 immediately before leaving, follow field signs rather than an old saved route and allow a larger buffer when arrival time matters.