Monday, October 5 · our forecast odds · issued Sun 1:00 PM ET · 10 nonstops

Tomorrow: DL 4031 at 14:30 is the safest bet, 16% chance of being 15+ min late; evening flights run 19–33%.

Safest bet that day DL 4031 SEA 14:30 → ONT 17:21 · 16% chance 15+ min late · usually 88% on time Riskiest AS 571 SEA 10:28 → ONT 13:16 · 39% chance 15+ min late · usually 52% on time

Against a calm day 27% average chance a nonstop arrives 15+ min late; 18% for the same flights on a calm-weather day

Every nonstop on Mon, Oct 5

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.


DL 4031 Delta flown by SkyWest Flight history →	SEA 14:30	ONT 17:21	16%	5%	0.5%	88%
DL 3884 Delta flown by SkyWest Flight history →	SEA 19:59	ONT 22:52	19%	6%	0.6%	84%
DL 4070 Delta flown by SkyWest Flight history →	SEA 08:25	ONT 11:17	22%	8%	0.5%	89%worse than usual
AS 1364 Alaska Flight history →	SEA 08:33	ONT 11:14	22%	5%	0.7%	90%worse than usual
AS 476 Alaska	SEA 07:27	ONT 10:14	22%	6%	0.7%	no record
F9 2276 Frontier Flight history →	SEA 11:54	ONT 14:45	30%	8%	0.9%	88%worse than usual
AS 489 Alaska Flight history →	SEA 20:33	ONT 23:11	33%	6%	0.6%	71%
AS 592 Alaska Flight history →	SEA 17:51	ONT 20:32	33%	6%	0.6%	75%
AS 565 Alaska Flight history →	SEA 10:25	ONT 13:09	35%	6%	0.7%	76%worse than usual
AS 571 Alaska Flight history →	SEA 10:28	ONT 13:16	39%	6%	0.7%	52%

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