Today looks rough: weather pushes the average chance of arriving 15+ min late to 59%, against 38% on a calm day. Safest: UA 2013 at 15:45, 45%.

Safest bet today UA 2013 DEN 15:45 → SEA 17:46 · 45% chance 15+ min late · usually 80% on time Riskiest WN 760 DEN 19:25 → SEA 21:25 · 78% chance 15+ min late

Weather 59% average chance a nonstop arrives 15+ min late; 38% 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. 18 flights that already left today are not shown.


UA 2013 United Flight history →	DEN 15:45	SEA 17:46	45%	11%	0.2%	80%worse than usual
AS 535 Alaska Flight history →	DEN 16:36	SEA 18:38	45%	9%	0.7%	67%worse than usual
AS 567 Alaska	DEN 15:30	SEA 17:21	47%	8%	0.7%	no record
UA 2651 United Flight history →	DEN 21:10	SEA 23:10	48%	11%	0.2%	72%worse than usual
AS 493 Alaska Flight history →	DEN 21:08	SEA 23:10	52%	9%	0.7%	57%
DL 2543 Delta Flight history →	DEN 18:39	SEA 20:41	55%	15%	0.5%	57%worse than usual
UA 360 United Flight history →	DEN 19:10	SEA 21:10	56%	14%	0.3%	69%worse than usual
UA 2767 United	DEN 19:11	SEA 21:00	58%	14%	0.3%	no record
AS 615 Alaska Flight history →	DEN 17:57	SEA 19:48	58%	10%	0.6%	58%worse than usual
AS 249 Alaska Flight history →	DEN 18:21	SEA 20:23	60%	12%	0.7%	58%worse than usual
WN 4030 Southwest	DEN 15:45	SEA 17:45	62%	9%	0.1%	no record
WN 3856 Southwest Flight history →	DEN 21:10	SEA 23:10	69%	14%	0.2%	28%
WN 4358 Southwest	DEN 21:15	SEA 23:02	72%	12%	0.2%	no record
WN 3245 Southwest	DEN 17:40	SEA 19:29	75%	14%	0.2%	no record
WN 760 Southwest	DEN 19:25	SEA 21:25	78%	17%	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