Thursday, October 8 · typical odds for a Thursday (too early for a weather forecast) · issued Sun 12:00 PM ET · 6 nonstops

Thu, Oct 8: DL 4031 at 14:30 is the safest bet, 13% chance of being 15+ min late; the others run 14–34%.

Safest bet that day DL 4031 SEA 14:30 → ONT 17:21 · 13% chance 15+ min late · usually 88% on time Riskiest AS 571 SEA 11:28 → ONT 14:01 · 34% chance 15+ min late · usually 52% on time

Every nonstop on Thu, Oct 8

12-month record →

Ranked by the chance of arriving 15+ minutes late (typical odds: the weather this date has had in past years), 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	13%	4%	0.6%	88%
DL 4070 Delta flown by SkyWest Flight history →	SEA 08:25	ONT 11:17	14%	5%	0.6%	89%
AS 1364 Alaska Flight history →	SEA 08:33	ONT 11:14	17%	3%	0.9%	90%
AS 592 Alaska Flight history →	SEA 17:51	ONT 20:32	22%	7%	0.7%	75%
F9 2276 Frontier Flight history →	SEA 11:54	ONT 14:45	22%	6%	0.8%	88%
AS 571 Alaska Flight history →	SEA 11:28	ONT 14:01	34%	5%	0.8%	52%

How these are worked out. Each flight’s odds are our forecast for that day (typical odds until the weather forecast covers it); 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 Thu, Oct 8 (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