Today: WN 1218 at 05:10 is the safest bet, 4% chance of being 15+ min late; evening flights run 25–30%.

Safest bet today WN 1218 COS 05:10 → DAL 08:00 · 4% chance 15+ min late · usually 92% on time Riskiest WN 1219 COS 16:40 → DAL 19:30 · 30% chance 15+ min late · usually 31% on time

Against a calm day 16% average chance a nonstop arrives 15+ min late; 13% 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 1218 Southwest Flight history →	COS 05:10	DAL 08:00	4%	1%	0.5%	92%
WN 1279 Southwest	COS 05:00	DAL 07:54	4%	1%	0.5%	no record
WN 2452 Southwest	COS 16:20	DAL 19:15	25%	4%	0.6%	no record
WN 1219 Southwest Flight history →	COS 16:40	DAL 19:30	30%	4%	0.6%	31%

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