Today looks rough: weather pushes the average chance of arriving 15+ min late to 49%, against 37% on a calm day. Safest: AS 704 at 20:15, 38%.

Safest bet today AS 704 SEA 20:15 → LAS 22:55 · 38% chance 15+ min late · usually 89% on time Riskiest WN 3757 SEA 20:20 → LAS 22:52 · 62% chance 15+ min late

Weather 49% average chance a nonstop arrives 15+ min late; 37% 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. 13 flights that already left today are not shown.


AS 704 Alaska Flight history →	SEA 20:15	LAS 22:55	38%	9%	0.6%	89%worse than usual
AS 636 Alaska Flight history →	SEA 21:23	LAS 23:59	42%	8%	0.6%	69%worse than usual
DL 2949 Delta Flight history →	SEA 20:34	LAS 23:10	43%	18%	0.4%	81%worse than usual
AS 768 Alaska Flight history →	SEA 20:23	LAS 22:50	45%	9%	0.6%	80%worse than usual
AS 678 Alaska Flight history →	SEA 17:23	LAS 19:51	45%	11%	0.6%	67%worse than usual
AS 523 Alaska	SEA 18:24	LAS 20:52	46%	9%	0.5%	no record
F9 4204 Frontier Flight history →	SEA 21:52	LAS 00:30	51%	22%	1.2%	70%worse than usual
F9 2408 Frontier Flight history →	SEA 20:53	LAS 23:34	55%	24%	1.3%	68%worse than usual
WN 1100 Southwest	SEA 19:45	LAS 22:25	60%	22%	0.2%	no record
WN 3757 Southwest	SEA 20:20	LAS 22:52	62%	21%	0.2%	no record

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 Sun, Oct 4 (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