How fog affects
flights at SEA.
Seattle-Tacoma International (SEA) in Seattle. Historical delay data, cancellation risk, airline performance, and what to do when fog hits. Season: Year-round.
Fog Impact at SEA
Based on historical flight performance data during Year-round
81%
On-time rate
during fog
1.0%
Cancellation
rate
58m
Avg delay
when late
No change
On-time rate drop
vs off-peak months
9 fog days/month
During
Year-round
What happens at SEA during fog
Fog reduces visibility below IFR minimums, forcing airports to cut arrival rates by 30-50%. Unlike storms that pass in hours, fog can persist all morning, creating a slow-building delay that ripples through the entire day's schedule.
Historical impact
During Year-round, SEA's on-time rate drops to 81% — compared to 0% during non-peak months. Cancellations rise from 0.0% to 1.0% during peak fog months.
Typical recovery time
Burns off by late morning in most cases (SFO: typically by noon). Morning flights are most affected; afternoon flights usually run on time.
Which airlines handle fog best at SEA?
All airlines are subject to the same runway closures and ground stops, but some handle disruption better than others — faster rebooking, better crew scheduling, and more de-icing capacity.
Best at SEA
85% on-time · 64m avg delay
Most delayed
Hawaiian Airlines
68% on-time · 65m avg delay
Based on overall performance at SEA. Individual flight performance varies by route and time of day.
Tips for flying through SEA during fog
Book afternoon flights
Fog at SEA typically burns off by midday. Flights after 1 PM have dramatically better on-time rates during fog season.
Check ceiling and visibility
If visibility drops below 1 mile or ceiling below 200 feet, expect significant delays. NWS observations update every hour.
Don't connect through fog-prone airports in the morning
A 7 AM connection through SEA during fog season is risky. Build in at least 3 hours if you must connect here.
Fog delays compound slowly
Unlike a thunderstorm that causes a sudden ground stop, fog creates a slow-building delay. Each hour of fog pushes the afternoon schedule back further.
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Common questions
How does fog affect flights at SEA?
During fog season, SEA averages a 81% on-time rate with an average delay of 58 minutes when flights are late. The cancellation rate during peak months is 1.0%.
What months are worst for fog at SEA?
Fog at SEA peaks during Year-round (worst Jun - Sep at SFO). These months show measurably higher delay and cancellation rates compared to the rest of the year.
Which airline handles fog best at SEA?
Based on historical data, null has the best on-time performance at SEA with a 85% on-time rate. However, all airlines are subject to the same runway and ground stop constraints during severe weather.
Do I get a refund if my SEA flight is cancelled due to fog?
Yes. Under federal law (14 CFR Part 260), you are entitled to a full cash refund if your flight is cancelled — regardless of the reason, including weather. The airline must refund to your original payment method within 7 business days for credit cards.
How long do fog delays last at SEA?
Burns off by late morning in most cases (SFO: typically by noon). Morning flights are most affected; afternoon flights usually run on time.
Other airports affected by fog