Today looks like a normal day here: all 3 nonstops are 33–39% likely to arrive 15+ min late.

Safest bet today WN 665 DCA 17:36 → DAL 19:54 · 33% chance 15+ min late Riskiest WN 4377 DCA 20:35 → DAL 22:55 · 39% chance 15+ min late · usually 38% on time

Against a calm day 37% average chance a nonstop arrives 15+ min late; 58% 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. 7 flights that already left today are not shown.


WN 665 Southwest	DCA 17:36	DAL 19:54	33%	9%	0.8%	no record
WN 4556 Southwest	DCA 20:11	DAL 22:30	39%	10%	0.7%	no record
WN 4377 Southwest Flight history →	DCA 20:35	DAL 22:55	39%	13%	0.7%	38%

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