Today: WN 434 at 10:45 is the safest bet, 9% chance of being 15+ min late; evening flights run 23–25%.

Safest bet today WN 434 BNA 10:45 → BHM 11:40 · 9% chance 15+ min late · usually 74% on time Riskiest WN 4559 BNA 22:50 → BHM 23:50 · 25% chance 15+ min late · usually 49% on time

Against a calm day 17% average chance a nonstop arrives 15+ min late; 18% 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 434 Southwest Flight history →	BNA 10:45	BHM 11:40	9%	2%	0.1%	74%
WN 225 Southwest	BNA 12:25	BHM 13:30	12%	2%	0.1%	no record
WN 4923 Southwest	BNA 22:20	BHM 23:25	23%	6%	0.5%	no record
WN 4559 Southwest Flight history →	BNA 22:50	BHM 23:50	25%	6%	0.5%	49%

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