Today: WN 1508 at 21:01 is the safest bet, 24% chance of being 15+ min late; the others run 26–35%.

Safest bet today WN 1508 DCA 21:01 → MDW 22:09 · 24% chance 15+ min late Riskiest WN 836 DCA 18:36 → MDW 19:44 · 35% chance 15+ min late

Against a calm day 29% average chance a nonstop arrives 15+ min late; 29% 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 1508 Southwest	DCA 21:01	MDW 22:09	24%	6%	0.5%	no record
WN 370 Southwest	DCA 21:35	MDW 22:40	26%	7%	0.6%	no record
WN 473 Southwest	DCA 15:06	MDW 16:13	28%	4%	0.4%	no record
WN 4479 Southwest Flight history →	DCA 15:10	MDW 16:15	28%	4%	0.4%	62%
WN 2852 Southwest	DCA 20:05	MDW 21:10	32%	6%	0.5%	no record
WN 836 Southwest	DCA 18:36	MDW 19:44	35%	6%	0.5%	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 Sun, Oct 4 (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