Today: WN 4049 at 10:20 is the safest bet, 5% chance of being 15+ min late; evening flights run 15–19%.

Safest bet today WN 4049 STL 10:20 → CLE 13:02 · 5% chance 15+ min late Riskiest WN 3210 STL 19:55 → CLE 22:37 · 19% chance 15+ min late

Against a calm day 12% average chance a nonstop arrives 15+ min late; 12% 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 4049 Southwest	STL 10:20	CLE 13:02	5%	1%	0.2%	no record
WN 3899 Southwest Flight history →	STL 12:50	CLE 15:20	9%	2%	0.2%	67%
WN 3900 Southwest Flight history →	STL 20:55	CLE 23:30	15%	4%	0.5%	69%
WN 3210 Southwest	STL 19:55	CLE 22:37	19%	5%	0.5%	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 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