Today: WN 4450 at 09:55 is the safest bet, 10% chance of being 15+ min late; evening flights run 24–30%.

Safest bet today WN 4450 MDW 09:55 → MKE 10:46 · 10% chance 15+ min late Riskiest WN 3238 MDW 21:40 → MKE 22:32 · 30% chance 15+ min late

Against a calm day 18% average chance a nonstop arrives 15+ min late; 19% 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 4450 Southwest	MDW 09:55	MKE 10:46	10%	1%	0.2%	no record
WN 1702 Southwest Flight history →	MDW 10:20	MKE 11:05	10%	1%	0.2%	90%
WN 2043 Southwest Flight history →	MDW 21:55	MKE 22:50	24%	6%	0.6%	59%
WN 3238 Southwest	MDW 21:40	MKE 22:32	30%	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