Today: WN 4 at 08:40 is the safest bet, 11% chance of being 15+ min late; evening flights run 26–28%.

Safest bet today WN 4 DAL 08:40 → BHM 10:29 · 11% chance 15+ min late · usually 98% on time Riskiest WN 1418 DAL 20:40 → BHM 22:29 · 28% chance 15+ min late

Against a calm day 22% average chance a nonstop arrives 15+ min late; 20% 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 4 Southwest Flight history →	DAL 08:40	BHM 10:29	11%	2%	0.2%	98%
WN 1271 Southwest Flight history →	DAL 09:50	BHM 11:30	16%	2%	0.2%	84%
WN 997 Southwest	DAL 15:55	BHM 17:44	23%	5%	0.6%	no record
WN 4389 Southwest Flight history →	DAL 16:25	BHM 18:05	26%	6%	0.6%	38%
WN 4390 Southwest Flight history →	DAL 20:15	BHM 22:00	28%	7%	0.6%	49%
WN 1418 Southwest	DAL 20:40	BHM 22:29	28%	6%	0.6%	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