Today: WN 3519 at 08:10 is the safest bet, 6% chance of being 15+ min late; evening flights run 20–22%.

Safest bet today WN 3519 PIT 08:10 → MDW 08:47 · 6% chance 15+ min late Riskiest WN 3521 PIT 19:45 → MDW 20:20 · 22% chance 15+ min late

Against a calm day 14% 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 3519 Southwest	PIT 08:10	MDW 08:47	6%	1%	0.1%	no record
WN 3378 Southwest Flight history →	PIT 08:45	MDW 09:10	8%	1%	0.1%	80%
WN 3520 Southwest	PIT 13:40	MDW 14:15	14%	2%	0.5%	no record
WN 4707 Southwest Flight history →	PIT 15:50	MDW 16:20	15%	3%	0.5%	73%
WN 4073 Southwest Flight history →	PIT 20:15	MDW 20:45	20%	3%	0.5%	71%
WN 3521 Southwest	PIT 19:45	MDW 20:20	22%	3%	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