Today: WN 1946 at 09:40 is the safest bet, 7% chance of being 15+ min late; evening flights run 20%.

Safest bet today WN 1946 MDW 09:40 → GRR 11:43 · 7% chance 15+ min late Riskiest WN 4572 MDW 21:45 → GRR 23:48 · 20% chance 15+ min late

Against a calm day 13% average chance a nonstop arrives 15+ min late; 13% 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 1946 Southwest	MDW 09:40	GRR 11:43	7%	1%	0.1%	no record
WN 2779 Southwest Flight history →	MDW 10:15	GRR 12:05	7%	2%	0.1%	90%
WN 4954 Southwest	MDW 15:05	GRR 17:07	11%	4%	0.1%	no record
WN 1893 Southwest Flight history →	MDW 13:15	GRR 15:05	11%	3%	0.1%	53%
WN 4113 Southwest Flight history →	MDW 21:25	GRR 23:25	20%	5%	0.6%	50%
WN 4572 Southwest	MDW 21:45	GRR 23:48	20%	5%	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