Today looks like a normal day here: all 4 nonstops are 18–20% likely to arrive 15+ min late.

Safest bet today WN 3632 SEA 09:00 → STL 14:50 · 18% chance 15+ min late · usually 90% on time Riskiest AS 618 SEA 18:03 → STL 23:51 · 20% chance 15+ min late · usually 92% on time

Against a calm day 19% average chance a nonstop arrives 15+ min late; 19% for the same flights on a calm-weather day

Every nonstop today

12-month record →

Ranked by the chance of arriving 15+ minutes late, with each flight’s on-time record over Aug 2025 – Jul 2026 beside it. Times are local. Pick a flight for its forecast. Click a column to sort.


WN 3632 Southwest Flight history →	SEA 09:00	STL 14:50	18%	3%	0.2%	90%
AS 647 Alaska Flight history →	SEA 09:40	STL 15:30	18%	3%	0.3%	88%
AS 615 Alaska Flight history →	SEA 18:04	STL 23:59	20%	4%	0.5%	87%
AS 618 Alaska Flight history →	SEA 18:03	STL 23:51	20%	4%	0.5%	92%worse than usual

Alternatives with one stop that day

All connections →


United Details →	SEA 05:00 → DEN 08:43UA 2601	52m Denver	DEN 09:35 → STL 12:42UA 652	5h 42m	86%	75%

How these are worked out. Each flight’s odds are our forecast for that day; flights of airlines we don’t forecast yet use their 12-month record and are marked. Makes the connection: the first flight’s 12-month lateness curve, scaled so its chance of arriving 15+ min late matches the day’s forecast, at the layover minus the 45-minute minimum (90 on separate tickets). Arrives on time: first flight not cancelled × connection made × second flight not cancelled × second flight within 15 minutes, each from the day’s forecast.

About this data: forecast odds from our model for Mon, Oct 5 (newest published update); 12-month records from US DOT on-time data, Aug 2025 – Jul 2026, all US airlines; regional flights count under the airline that sells them. JSON