Today: WN 3877 at 10:00 is the safest bet, 7% chance of being 15+ min late; evening flights run 17–23%.

Safest bet today WN 3877 MDW 10:00 → IND 12:05 · 7% chance 15+ min late · usually 84% on time Riskiest WN 3190 MDW 21:25 → IND 23:30 · 23% chance 15+ min late · usually 55% on time

Against a calm day 13% average chance a nonstop arrives 15+ min late; 15% 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 3877 Southwest Flight history →	MDW 10:00	IND 12:05	7%	2%	0.2%	84%
WN 2699 Southwest	MDW 09:50	IND 11:54	7%	2%	0.2%	no record
WN 2896 Southwest	MDW 22:15	IND 00:19	17%	4%	0.6%	no record
WN 3190 Southwest Flight history →	MDW 21:25	IND 23:30	23%	4%	0.5%	55%

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