Today looks rough: weather pushes the average chance of arriving 15+ min late to 49%, against 33% on a calm day. Safest: AS 536 at 23:18, 42%.

Safest bet today AS 536 SEA 23:18 → BOS 07:40 · 42% chance 15+ min late · usually 78% on time Riskiest B6 198 SEA 23:46 → BOS 08:04 · 62% chance 15+ min late · usually 53% on time

Weather 49% average chance a nonstop arrives 15+ min late; 33% 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. 10 flights that already left today are not shown.


AS 536 Alaska Flight history →	SEA 23:18	BOS 07:40	42%	6%	0.6%	78%worse than usual
AS 214 Alaska Flight history →	SEA 23:00	BOS 07:12	42%	7%	0.7%	81%worse than usual
B6 198 JetBlue Flight history →	SEA 23:46	BOS 08:04	62%	29%	0.8%	53%worse than usual

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