Sunday, October 11 · typical odds for a Sunday (too early for a weather forecast) · issued Mon 12:00 AM ET · 7 nonstops

Sun, Oct 11: DL 4070 at 11:59 is the safest bet, 12% chance of being 15+ min late; evening flights run 18–40%.

Safest bet that day DL 4070 ONT 11:59 → SEA 14:51 · 12% chance 15+ min late · usually 91% on time Riskiest AS 592 ONT 18:56 → SEA 21:33 · 40% chance 15+ min late · usually 71% on time

Every nonstop on Sun, Oct 11

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 4070 Delta flown by SkyWest Flight history →	ONT 11:59	SEA 14:51	12%	4%	0.9%	91%
AS 607 Alaska Flight history →	ONT 06:02	SEA 08:44	12%	2%	1.3%	93%
DL 4031 Delta flown by SkyWest Flight history →	ONT 18:01	SEA 20:50	18%	6%	0.8%	90%
AS 475 Alaska	ONT 11:13	SEA 13:51	19%	3%	2.1%	no record
F9 2275 Frontier Flight history →	ONT 16:49	SEA 19:38	29%	8%	1.2%	80%
AS 575 Alaska Flight history →	ONT 14:10	SEA 16:47	35%	5%	2.0%	61%
AS 592 Alaska Flight history →	ONT 18:56	SEA 21:33	40%	8%	1.5%	71%worse than usual

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 Sun, Oct 11 (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