Friday, October 9 · typical odds for a Friday (too early for a weather forecast) · issued Sun 4:00 PM ET · 3 nonstops

Fri, Oct 9: WN 3985 at 05:00 is the safest bet, 3% chance of being 15+ min late; the others run 9–30%.

Safest bet that day WN 3985 STL 05:00 → TPA 08:20 · 3% chance 15+ min late · usually 95% on time Riskiest WN 4619 STL 20:15 → TPA 23:35 · 30% chance 15+ min late · usually 52% 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 3985 Southwest Flight history →	STL 05:00	TPA 08:20	3%	1%	16.5%	95%
WN 3986 Southwest Flight history →	STL 10:05	TPA 13:25	9%	3%	17.1%	91%
WN 4619 Southwest Flight history →	STL 20:15	TPA 23:35	30%	8%	7.1%	52%

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