Today: WN 297 at 09:55 is the safest bet, 5% chance of being 15+ min late; evening flights run 16–23%.

Safest bet today WN 297 STL 09:55 → RDU 12:45 · 5% chance 15+ min late · usually 88% on time Riskiest WN 3810 STL 19:55 → RDU 22:50 · 23% chance 15+ min late · usually 58% on time

Against a calm day 12% average chance a nonstop arrives 15+ min late; 13% 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.


WN 297 Southwest Flight history →	STL 09:55	RDU 12:45	5%	1%	0.2%	88%
WN 4118 Southwest	STL 10:20	RDU 13:20	5%	1%	0.2%	no record
WN 278 Southwest	STL 20:34	RDU 23:34	16%	3%	0.5%	no record
WN 3810 Southwest Flight history →	STL 19:55	RDU 22:50	23%	4%	0.5%	58%

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