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 4031 at 05:20 is the safest bet, 4% chance of being 15+ min late; the others run 8–27%.

Safest bet that day WN 4031 TPA 05:20 → MDW 07:00 · 4% chance 15+ min late · usually 94% on time Riskiest WN 4035 TPA 22:30 → MDW 00:10 · 27% chance 15+ min late · usually 69% 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 4031 Southwest Flight history →	TPA 05:20	MDW 07:00	4%	1%	14.9%	94%
WN 2869 Southwest Flight history →	TPA 08:00	MDW 09:40	8%	2%	16.0%	81%
WN 4033 Southwest Flight history →	TPA 10:45	MDW 12:25	15%	3%	17.2%	78%
WN 4035 Southwest Flight history →	TPA 22:30	MDW 00:10	27%	10%	13.2%	69%

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