Today: WN 1866 at 05:55 is the safest bet, 3% chance of being 15+ min late; evening flights run 30–31%.

Safest bet today WN 1866 FLL 05:55 → MDW 07:55 · 3% chance 15+ min late · usually 96% on time Riskiest WN 1928 FLL 18:25 → MDW 20:40 · 31% chance 15+ min late

Against a calm day 18% average chance a nonstop arrives 15+ min late; 14% 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 1866 Southwest Flight history →	FLL 05:55	MDW 07:55	3%	1%	0.2%	96%
WN 4979 Southwest	FLL 06:35	MDW 08:50	4%	1%	0.2%	no record
WN 1869 Southwest Flight history →	FLL 10:15	MDW 12:15	17%	4%	0.1%	80%
WN 1927 Southwest	FLL 12:55	MDW 15:11	21%	4%	0.1%	no record
WN 1870 Southwest Flight history →	FLL 18:20	MDW 20:25	30%	6%	0.5%	39%
WN 1928 Southwest	FLL 18:25	MDW 20:40	31%	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