Monday, October 5 · our forecast odds · issued Sun 9:00 AM ET · 9 nonstops

Tomorrow: DL 4070 at 11:59 is the safest bet, 7% chance of being 15+ min late; evening flights run 8–20%.

Safest bet that day DL 4070 ONT 11:59 → SEA 14:51 · 7% chance 15+ min late · usually 91% on time Riskiest AS 594 ONT 21:20 → SEA 23:59 · 20% chance 15+ min late · usually 67% on time

Against a calm day 14% average chance a nonstop arrives 15+ min late; 12% 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 4070 Delta flown by SkyWest Flight history →	ONT 11:59	SEA 14:51	7%	3%	0.5%	91%
DL 3816 Delta flown by SkyWest Flight history →	ONT 06:20	SEA 09:15	8%	3%	0.6%	94%
DL 4031 Delta flown by SkyWest Flight history →	ONT 18:01	SEA 20:50	8%	4%	0.5%	90%
AS 607 Alaska Flight history →	ONT 06:02	SEA 08:44	11%	2%	0.8%	93%
AS 654 Alaska Flight history →	ONT 12:04	SEA 14:44	14%	3%	0.7%	90%
F9 2275 Frontier Flight history →	ONT 16:49	SEA 19:38	19%	7%	0.9%	80%
AS 567 Alaska Flight history →	ONT 14:05	SEA 16:45	19%	3%	0.7%	77%
AS 575 Alaska Flight history →	ONT 17:26	SEA 20:06	20%	5%	0.7%	61%
AS 594 Alaska Flight history →	ONT 21:20	SEA 23:59	20%	5%	0.8%	67%

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