Today looks rough: weather pushes the average chance of arriving 15+ min late to 46%, against 33% on a calm day. Safest: WN 647 at 20:06, 40%.

Safest bet today WN 647 BNA 20:06 → MDW 21:50 · 40% chance 15+ min late · usually 95% on time Riskiest WN 4836 BNA 18:00 → MDW 19:30 · 50% chance 15+ min late

Weather 46% average chance a nonstop arrives 15+ min late; 33% 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. 6 flights that already left today are not shown.


WN 647 Southwest Flight history →	BNA 20:06	MDW 21:50	40%	9%	0.2%	95%worse than usual
WN 4548 Southwest	BNA 22:36	MDW 00:20	46%	9%	0.2%	no record
WN 3390 Southwest	BNA 17:49	MDW 19:33	47%	8%	0.2%	no record
WN 4277 Southwest	BNA 20:15	MDW 21:45	48%	9%	0.2%	no record
WN 4836 Southwest	BNA 18:00	MDW 19:30	50%	9%	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