Today: WN 4574 at 07:55 is the safest bet, 9% chance of being 15+ min late; the others run 11–31%.

Safest bet today WN 4574 LGB 07:55 → DEN 11:10 · 9% chance 15+ min late · usually 100% on time Riskiest WN 2479 LGB 14:50 → DEN 18:05 · 31% chance 15+ min late · usually 41% on time

Against a calm day 18% average chance a nonstop arrives 15+ min late; 10% 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 4574 Southwest Flight history →	LGB 07:55	DEN 11:10	9%	1%	0.1%	100%
WN 342 Southwest	LGB 07:35	DEN 10:52	11%	1%	0.1%	no record
WN 4238 Southwest Flight history →	LGB 09:45	DEN 13:00	11%	2%	0.1%	84%
WN 2555 Southwest	LGB 11:50	DEN 15:06	17%	3%	0.1%	no record
WN 2556 Southwest	LGB 14:40	DEN 17:56	26%	4%	0.1%	no record
WN 2479 Southwest Flight history →	LGB 14:50	DEN 18:05	31%	4%	0.1%	41%

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