Image credit: Famartin via Wikimedia Commons, CC BY-SA 4.0. License: CC BY-SA 4.0.
Caltrans is closing all northbound lanes on U.S. 101 through San Francisco’s Hospital Curve for two full Labor Day-season weekends. Drivers headed to downtown, the Bay Bridge, or hotels after an SFO landing need a detour plan before Friday night traffic builds.
According to a Caltrans District 4 advisory, the first full northbound shutdown runs from 11 p.m. Friday, September 4, through 6 a.m. Monday, September 7. A second northbound window follows from 11 p.m. Friday, September 18, through 6 a.m. Monday, September 21.
- Where: Northbound U.S. 101 Bayshore Freeway (Hospital Curve) between Cesar Chavez Street and 10th Street in San Francisco.
- First full close: Friday, Sept. 4, 11 p.m., to Monday, Sept. 7, 6 a.m.
- Second full close: Friday, Sept. 18, 11 p.m., to Monday, Sept. 21, 6 a.m.
- Southbound: Remains open during those northbound weekends. October southbound windows are still being refined on local advisories.
- Best bypass: Northbound I-280 toward downtown or the Bay Bridge, or exit at Cesar Chavez and use Potrero Avenue.
What Caltrans locked in for Labor Day weekend
Caltrans says crews will run around-the-clock pavement repairs on the Hospital Curve segment of the Bayshore Freeway. The agency is treating these as full directional closures, not partial lane reductions.
Southbound lanes stay open while northbound traffic is shut. That still leaves a narrow corridor next to a live work zone, so Caltrans is telling drivers to stay far away from the curve if they can.
SFist reported the same September northbound windows and added that each closure is expected to last about 55 hours. That matches Caltrans’ Friday-night-to-Monday-morning schedule.
The Labor Day timing is deliberate. Caltrans told local reporters that holiday weekend traffic skews toward leisure trips and away from weekday commuting, which can make a full rebuild window more workable even when AAA expects busy Bay Area roads.
Weather still controls the schedule. Caltrans notes the pavement work is weather dependent, and summer conditions are part of why the agency wants these September windows now.
How the detours change an SFO or downtown trip
If you are driving north from the Peninsula or San Francisco International Airport toward downtown hotels, Chase Center, or the Bay Bridge, do not assume the usual Bayshore Freeway hop still works on those nights.
Caltrans’ preferred bypass is northbound I-280. From SFO and South Bay approaches, that usually means peeling onto I-380 or related connectors early enough to reach I-280 before you are committed to the Hospital Curve segment.
Caltrans also published a dedicated detour map for airport and Peninsula travelers. Recheck it the day you drive, because ramp assignments and message boards can change as crews stage equipment.
The other city-side option is to leave U.S. 101 at Cesar Chavez Street and continue on Potrero Avenue through the Mission. That route can absorb overflow, and Caltrans has already warned nearby hospitals and emergency services to expect heavier surface traffic.
For trip planning beyond the freeway itself, Deep Arrival’s San Francisco things to do guide helps you decide whether a downtown hotel base or a Peninsula stay better fits a weekend when Hospital Curve is offline.
Why Hospital Curve keeps coming up
Hospital Curve is the Bayshore Freeway bend near Zuckerberg San Francisco General Hospital. It sits on one of the region’s most used approaches into the city and toward the Bay Bridge.
The current work belongs to Caltrans’ longer Fab 4 rehabilitation package for San Francisco freeways. The Hospital Curve project began in fall 2025 and is expected to continue into later years as pavement, drainage, and median barrier work proceed in stages.
Caltrans finished a preparatory drainage weekend ahead of schedule on August 24, 2026, after partial closures that began August 21.
Bay Area drivers already saw a related access squeeze when the Carquinez Bridge closure disrupted SFO weekend road access. Hospital Curve is a separate stream with the same rule: do not leave a same-day airport transfer to chance.
October southbound windows are still a watch item
Caltrans’ August 19 advisory firmly schedules the two northbound September weekends. Southbound full closures are a separate phase.
SFist, summarizing local reporting, said southbound weekends are expected to begin Friday, October 2, and again around October 17. Treat those October dates as directionally useful until Caltrans posts a matching southbound advisory with exact open and close times.
SFMTA has also flagged October Caltrans weekends on city advisories. That is useful corroboration for city travelers.
Caltrans QuickMap and District 4 pages remain the controlling lane-status source. If October plans depend on southbound U.S. 101 through the Mission, recheck the week before you freeze a same-day airport transfer.
What to do before you book a car or hotel
Labor Day weekend travelers should decide now whether they need northbound U.S. 101 at all. A Peninsula hotel, BART connection, or rideshare that never enters Hospital Curve can be cleaner than a late Friday freeway gamble.
If you must drive, leave earlier than the app suggests and preselect I-280. Build a Potrero Avenue backup in case message boards force an earlier exit at Cesar Chavez.
Event travelers should note the September 18 to 21 window overlaps busy downtown nights. SFist reported Caltrans coordinating around a Chase Center schedule during that second northbound close.
Keep screenshots or saved maps of the I-280 path and the Cesar Chavez exit before you leave the airport curb. Cellular coverage and app reroutes get noisy when message boards and temporary cones appear at once.
If you are traveling with a tight flight connection the morning after a closure weekend, assume Monday 6 a.m. is the earliest reopen and leave extra buffer for residual lane shifts.
| If you… | Do this |
|---|---|
| Land at SFO on Sept. 4 to 7 or Sept. 18 to 21 and need downtown | Preselect northbound I-280. Do not wait until you are on Bayshore approaching Hospital Curve. |
| Are driving to the Bay Bridge from the Peninsula | Use Caltrans’ I-280 Bay Bridge path and ignore the usual U.S. 101 shortcut during the northbound closes. |
| Have a Chase Center or downtown hotel arrival after 11 p.m. Friday | Assume Hospital Curve is already dark. Add 30 to 45 minutes and a Potrero Avenue backup. |
| Only need southbound U.S. 101 in September | Southbound stays open in the Caltrans September windows, but expect work-zone congestion beside the closed direction. |
| Are planning an October southbound trip through the Mission | Recheck Caltrans for the final October southbound advisory before you lock a same-day airport transfer. |
Northbound U.S. 101 through San Francisco’s Hospital Curve is scheduled dark for two full weekends starting Labor Day. Rebuild SFO-to-downtown and Peninsula-to-Bay Bridge routes around I-280 now, and treat October southbound dates as provisional until Caltrans posts matching times.
The practical move is simple. If your Labor Day or mid-September itinerary needs northbound Bayshore Freeway through the Mission, change the route before Friday night, not after the cones appear.
When does northbound U.S. 101 close in San Francisco for Labor Day?
Caltrans says all northbound Hospital Curve lanes close at 11 p.m. Friday, September 4, 2026, and reopen by 6 a.m. Monday, September 7.
Is there a second September closure?
Yes. Caltrans schedules another full northbound close from 11 p.m. Friday, September 18, through 6 a.m. Monday, September 21.
Which segment is closed?
The Bayshore Freeway Hospital Curve between Cesar Chavez Street and 10th Street in San Francisco, according to the Caltrans August 19 advisory.
What is the best detour from SFO?
Caltrans points drivers to northbound I-280 toward downtown or the Bay Bridge, with Cesar Chavez to Potrero Avenue as a city-street backup.
Are southbound lanes closed too?
Not during the two September northbound weekends Caltrans has confirmed. October southbound weekends have been reported locally and should be rechecked on Caltrans before travel.
