Saturday, October 10 · typical odds for a Saturday (too early for a weather forecast) · issued Sun 12:00 AM ET · 6 nonstops

Sat, Oct 10: DL 4031 at 14:30 is the safest bet, 15% chance of being 15+ min late; the others run 17–29%.

Safest bet that day DL 4031 SEA 14:30 → ONT 17:21 · 15% chance 15+ min late · usually 88% on time Riskiest AS 571 SEA 10:29 → ONT 13:04 · 29% chance 15+ min late · usually 52% on time

Every nonstop on Sat, Oct 10

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	15%	4%	0.6%	88%
AS 476 Alaska	SEA 07:46	ONT 10:22	17%	3%	0.9%	no record
DL 3884 Delta flown by SkyWest Flight history →	SEA 19:59	ONT 22:52	18%	6%	0.9%	84%
F9 2276 Frontier Flight history →	SEA 11:54	ONT 14:45	19%	5%	0.8%	88%
AS 592 Alaska Flight history →	SEA 15:24	ONT 17:58	27%	7%	0.8%	75%
AS 571 Alaska Flight history →	SEA 10:29	ONT 13:04	29%	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 Sat, Oct 10 (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