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The Washington State Department of Transportation says overlapping highway closures from Thursday, October 1, through Monday, October 5, 2026, will lengthen trips across the Puget Sound region, including drives to Seattle-Tacoma International Airport. The WSDOT notice posted September 28 names work on Interstate 5, Interstate 405, State Route 520, and State Route 99, and it tells airport-bound drivers to expect congestion and less predictable travel times.
The airport-specific pinch is southbound I-405 in Tukwila on Saturday night into Sunday afternoon, when WSDOT will drop lanes and close a HOV ramp that feeds Sea-Tac trips. If you are flying out of SEA this weekend, add buffer before you leave a hotel or the Seattle cruise port to airport transfer, then confirm the live map the morning you roll. KIRO 7 repeated the same Tukwila window on September 30.
- Window: Thursday, October 1, through Monday, October 5, 2026.
- Airport hit: Southbound I-405 in Tukwila, 7 p.m. Saturday, October 3, to 1:30 p.m. Sunday, October 4, plus a HOV ramp closure that WSDOT says affects Sea-Tac trips.
- Other full closures: I-5 express lanes and eastbound SR 520 from I-5 to Montlake, 11 p.m. Friday, October 2, to 5 a.m. Monday, October 5.
- Kirkland: I-405 Exit 18 ramps close Thursday night and again Friday night through Monday morning.
- Weather: WSDOT says much of the work needs dry weather and may move if it rains.
I-405 Tukwila Work Hits Sea-Tac Access October 3 to 4
WSDOT will close up to two lanes on southbound I-405 in Tukwila from 7 p.m. Saturday, October 3, to 1:30 p.m. Sunday, October 4. The southbound I-405 HOV off-ramp to northbound I-405 closes in the same window. The agency says that ramp closure affects trips to Seattle-Tacoma International Airport. KIRO 7, writing from Tukwila, quoted WSDOT telling airport-bound drivers to plan for longer times and congestion on southbound I-405.
This is a road-access story, not a runway story. Flights still operate under the airport’s own notices, including the separate center-runway work already on the site. The decision is whether your drive from downtown, Bellevue, or a cruise terminal still fits a two-hour airport buffer once I-405 loses lanes.
Use Link light rail or a scheduled airport bus if your hotel is on a rail line. Drivers should treat Saturday night and Sunday morning as the highest-risk window for a missed check-in, not Friday afternoon, unless another listed closure sits on your exact path.
I-5 Express Lanes and SR 520 Close Friday Night Through Monday
The I-5 express lanes through Seattle close from 11 p.m. Friday, October 2, to 5 a.m. Monday, October 5. Crews on the Revive I-5 Ship Canal Bridge Preservation project will use the closure to reach the underside of the bridge for drainage work. WSDOT notes the express lanes have only been open northbound during construction, and northbound mainline I-5 remains reduced to two lanes across the Ship Canal Bridge.
Eastbound SR 520 between I-5 and Montlake Boulevard closes in the same Friday-to-Monday block. All traffic from I-5 that wants eastbound SR 520 must use another route. The Montlake Boulevard on-ramp to eastbound SR 520 stays open. Crews will prepare sections of the existing bridge and leftover pieces of the old Montlake off-ramp for removal as part of the SR 520 Portage Bay Bridge and Roanoke Lid Project.
If you are connecting a downtown Seattle stay to a Sunday morning SEA departure, do not count on the express lanes or that eastbound 520 segment. Build the drive on remaining mainline I-5, I-405, or rail, and keep the Seattle neighborhood stay guide in mind if a closer-to-rail hotel still saves the morning.
Kirkland I-405 Ramps Close Thursday Night and All Weekend
The I-405 and Northeast 85th Street interchange in Kirkland, Exit 18, closes in two pieces. Northbound and southbound ramps shut from 9 p.m. Thursday, October 1, to 5 a.m. Friday, October 2, then again from 10 p.m. Friday, October 2, to 5 a.m. Monday, October 5. Northeast 85th Street also closes between Sixth Street and 120th Avenue Northeast. Detours will be posted. Crews will pave Northeast 85th Street as part of the interchange and inline bus-rapid-transit station project.
Eastside travelers using that interchange to reach I-405 toward Tukwila and Sea-Tac lose the ramps for most of the weekend. WSDOT’s Engage board for the I-405 and SR 167 program repeats the same Thursday-night and Friday-to-Monday ramp hours and warns that detours cannot handle typical volumes.
Pair this with the Tukwila lane drop and you get a stacked I-405 problem: Kirkland ramps dark for the weekend, then southbound Tukwila lanes dark Saturday night into Sunday. An Eastside-to-airport drive that looks normal on a map is the one that needs the largest time pad.
SR 99 Tunnel and Aurora Bridge Add Overnight Cuts
The SR 99 Tunnel closes from 10 p.m. Friday, October 2, to 6 a.m. Saturday, October 3, for routine maintenance. That overnight cut sits on the same Friday night as the I-5 express-lane and SR 520 starts. A late downtown-to-airport ride that uses the tunnel should move to I-5 or surface streets before 10 p.m. Friday.
On the Aurora Bridge, the two right southbound lanes close from 5 a.m. to 11:30 a.m. Saturday, October 3, and the two right northbound lanes close from 5 a.m. to 11:30 a.m. Sunday, October 4, for inspections. Those are morning lane drops, not full closures, but they stack with the Saturday-to-Sunday I-405 work.
WSDOT says delays may show up in new places and at new times, and that rain can push work. Check the Travel Center map and King County email alerts before you leave. For a broader airline-side briefing after you clear the roads, the airlines hub is the next stop, not a substitute for the drive plan.
| If you… | What to do |
|---|---|
| Fly out of Sea-Tac on Sunday, October 4 | Leave extra time for southbound I-405 in Tukwila until 1:30 p.m. Prefer Link light rail if you can reach a station with luggage. |
| Drive from Kirkland or Bellevue to SEA this weekend | Exit 18 ramps are closed Friday night through Monday morning. Use a posted detour and add more than a usual I-405 pad. |
| Need I-5 express lanes Friday night to Monday | They are closed 11 p.m. October 2 to 5 a.m. October 5. Stay on mainline I-5 and expect the Ship Canal two-lane squeeze. |
| Have a late Friday downtown-to-airport ride | The SR 99 Tunnel closes at 10 p.m. October 2. Move the trip earlier or off SR 99. |
October 1 at 9 p.m. is the first Kirkland ramp closure. Eastside-to-I-405 trips should already be on a detour plan that night.
October 2 at 11 p.m. starts the I-5 express-lane and eastbound SR 520 weekend closures. Do not route a Saturday morning airport run through those facilities.
October 3 at 7 p.m. starts the Tukwila I-405 lane drop through 1:30 p.m. October 4. That is the named Sea-Tac access window. Recheck WSDOT if rain moved the work.
Will highway construction affect Sea-Tac this weekend?
Yes. WSDOT says southbound I-405 lane reductions in Tukwila from 7 p.m. October 3 to 1:30 p.m. October 4, plus a HOV ramp closure, affect trips to Seattle-Tacoma International Airport.
When do the I-5 express lanes close?
From 11 p.m. Friday, October 2, to 5 a.m. Monday, October 5. Northbound mainline I-5 stays reduced to two lanes across the Ship Canal Bridge.
Is SR 520 closed to the Eastside?
Eastbound SR 520 between I-5 and Montlake Boulevard is closed in that same Friday-to-Monday window. The Montlake on-ramp to eastbound SR 520 remains open.
When does the Kirkland I-405 Exit 18 interchange close?
Ramps close 9 p.m. October 1 to 5 a.m. October 2, then 10 p.m. October 2 to 5 a.m. October 5. Northeast 85th Street also closes between Sixth Street and 120th Avenue Northeast.
Does this cancel flights at Sea-Tac?
WSDOT is talking about highway access, not the flight schedule. Confirm your airline and the airport’s own notices separately, including the center-runway work already in effect.
Can rain cancel the closures?
WSDOT says much of this work needs good weather and may be rescheduled. Check the Travel Center map before you leave.
