Today: WN 339 at 12:55 is the safest bet, 26% chance of being 15+ min late; evening flights run 38–46%.

Safest bet today WN 339 STL 12:55 → DAL 14:35 · 26% chance 15+ min late Riskiest WN 4055 STL 19:20 → DAL 21:11 · 46% chance 15+ min late

Against a calm day 38% average chance a nonstop arrives 15+ min late; 34% 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. 4 flights that already left today are not shown.


WN 339 Southwest	STL 12:55	DAL 14:35	26%	3%	0.4%	no record
WN 2793 Southwest	STL 13:16	DAL 15:07	29%	4%	0.4%	no record
WN 3597 Southwest Flight history →	STL 15:05	DAL 16:45	37%	6%	0.4%	53%
WN 2321 Southwest	STL 16:35	DAL 18:26	38%	8%	0.4%	no record
WN 962 Southwest	STL 20:20	DAL 22:00	43%	7%	0.4%	no record
WN 4056 Southwest	STL 21:45	DAL 23:36	43%	8%	0.4%	no record
WN 3904 Southwest Flight history →	STL 21:50	DAL 23:30	44%	8%	0.4%	30%
WN 4055 Southwest	STL 19:20	DAL 21:11	46%	9%	0.4%	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