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 3513 at 06:30 is the safest bet, 9% chance of being 15+ min late; evening flights run 15–34%.

Safest bet that day WN 3513 SAN 06:30 → MDW 12:35 · 9% chance 15+ min late · usually 84% on time Riskiest WN 3448 SAN 17:30 → MDW 23:30 · 34% chance 15+ min late · usually 50% 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 3513 Southwest Flight history →	SAN 06:30	MDW 12:35	9%	1%	0.8%	84%
WN 257 Southwest Flight history →	SAN 22:40	MDW 04:40	15%	4%	1.1%	92%
WN 4163 Southwest Flight history →	SAN 12:10	MDW 18:10	27%	6%	0.8%	50%
WN 3448 Southwest Flight history →	SAN 17:30	MDW 23:30	34%	9%	0.8%	50%

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