Monday, October 5 · our forecast odds · issued Sun 12:00 PM ET · 4 nonstops

Tomorrow: UA 2661 at 10:40 is the safest bet, 18% chance of being 15+ min late; evening flights run 20–30%.

Safest bet that day UA 2661 SFO 10:40 → ONT 12:12 · 18% chance 15+ min late · usually 78% on time Riskiest UA 5613 SFO 16:17 → ONT 17:54 · 30% chance 15+ min late · usually 67% on time

Against a calm day 23% average chance a nonstop arrives 15+ min late; 22% 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.


UA 2661 United Flight history →	SFO 10:40	ONT 12:12	18%	5%	0.5%	78%
UA 552 United Flight history →	SFO 21:00	ONT 22:37	20%	8%	0.5%	83%
F9 2678 Frontier Flight history →	SFO 09:33	ONT 11:07	26%	9%	1.3%	58%
UA 5613 United flown by SkyWest Flight history →	SFO 16:17	ONT 17:54	30%	13%	0.7%	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