Friday, October 9 · typical odds for a Friday (too early for a weather forecast) · issued Sun 4:00 PM ET · 4 nonstops

Fri, Oct 9: WN 4171 at 08:55 is the safest bet, 6% chance of being 15+ min late; evening flights run 17–20%.

Safest bet that day WN 4171 CLE 08:55 → MDW 09:10 · 6% chance 15+ min late · usually 88% on time Riskiest WN 1163 CLE 20:10 → MDW 20:25 · 20% chance 15+ min late · usually 71% on time

Every nonstop on Fri, Oct 9

12-month record →

Ranked by the chance of arriving 15+ minutes late (typical odds: the weather this date has had in past years), 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 4171 Southwest Flight history →	CLE 08:55	MDW 09:10	6%	2%	0.6%	88%
WN 1161 Southwest Flight history →	CLE 12:05	MDW 12:20	12%	3%	0.6%	88%
WN 1162 Southwest Flight history →	CLE 16:45	MDW 17:05	17%	4%	0.6%	82%
WN 1163 Southwest Flight history →	CLE 20:10	MDW 20:25	20%	5%	0.6%	71%

How these are worked out. Each flight’s odds are our forecast for that day (typical odds until the weather forecast covers it); 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 Fri, Oct 9 (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