Today looks rough: weather pushes the average chance of arriving 15+ min late to 47%, against 32% on a calm day. Safest: UA 2633 at 15:47, 30%.

Safest bet today UA 2633 DEN 15:47 → SFO 17:30 · 30% chance 15+ min late · usually 73% on time Riskiest WN 1773 DEN 18:35 → SFO 20:19 · 65% chance 15+ min late

Weather 47% average chance a nonstop arrives 15+ min late; 32% for the same flights on a calm-weather day

Every nonstop today

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. 12 flights that already left today are not shown.


UA 2633 United Flight history →	DEN 15:47	SFO 17:30	30%	8%	0.2%	73%
UA 1007 United Flight history →	DEN 17:54	SFO 19:40	36%	11%	0.2%	68%
UA 2123 United Flight history →	DEN 21:10	SFO 22:56	38%	10%	0.2%	60%
UA 1389 United Flight history →	DEN 19:25	SFO 21:11	42%	12%	0.2%	44%
F9 3439 Frontier Flight history →	DEN 22:29	SFO 00:23	47%	19%	1.0%	70%worse than usual
WN 4670 Southwest Flight history →	DEN 16:55	SFO 18:30	50%	10%	0.2%	21%
WN 3297 Southwest	DEN 21:35	SFO 23:17	55%	12%	0.2%	no record
F9 1093 Frontier Flight history →	DEN 18:58	SFO 20:54	60%	22%	1.1%	62%worse than usual
WN 1773 Southwest	DEN 18:35	SFO 20:19	65%	12%	0.2%	no record

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 Sun, Oct 4 (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