Today looks rough: weather pushes the average chance of arriving 15+ min late to 45%, against 26% on a calm day. Safest: AS 398 at 23:57, 33%.

Safest bet today AS 398 SEA 23:57 → IAH 06:20 · 33% chance 15+ min late · usually 82% on time Riskiest AS 240 SEA 17:36 → IAH 23:47 · 60% chance 15+ min late

Weather 45% average chance a nonstop arrives 15+ min late; 26% 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. 6 flights that already left today are not shown.


AS 398 Alaska Flight history →	SEA 23:57	IAH 06:20	33%	5%	0.7%	82%worse than usual
UA 2379 United Flight history →	SEA 23:52	IAH 06:13	35%	10%	0.8%	84%worse than usual
UA 1660 United Flight history →	SEA 17:00	IAH 23:26	38%	8%	0.3%	84%worse than usual
AS 1573 Alaska Flight history →	SEA 17:33	IAH 23:59	60%	19%	0.6%	63%worse than usual
AS 240 Alaska	SEA 17:36	IAH 23:47	60%	18%	0.6%	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