Today: WN 1676 at 14:37 is the safest bet, 25% chance of being 15+ min late; evening flights run 31–39%.

Safest bet today WN 1676 DEN 14:37 → MDW 18:02 · 25% chance 15+ min late Riskiest WN 1683 DEN 20:55 → MDW 00:21 · 39% chance 15+ min late

Against a calm day 31% average chance a nonstop arrives 15+ min late; 22% 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 1676 Southwest	DEN 14:37	MDW 18:02	25%	6%	0.3%	no record
WN 1603 Southwest Flight history →	DEN 15:50	MDW 19:15	30%	7%	0.2%	61%
WN 1604 Southwest Flight history →	DEN 17:35	MDW 21:00	31%	8%	0.3%	27%
WN 2565 Southwest	DEN 17:57	MDW 21:22	31%	7%	0.3%	no record
WN 2775 Southwest	DEN 18:55	MDW 22:21	33%	7%	0.3%	no record
WN 1683 Southwest	DEN 20:55	MDW 00:21	39%	8%	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 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