Friday, October 9 · typical odds for a Friday (too early for a weather forecast) · issued Sun 4:00 PM ET · 6 nonstops

Fri, Oct 9: WN 3934 at 06:10 is the safest bet, 4% chance of being 15+ min late; evening flights run 28–31%.

Safest bet that day WN 3934 STL 06:10 → LAS 07:35 · 4% chance 15+ min late · usually 88% on time Riskiest WN 3935 STL 19:45 → LAS 21:10 · 31% chance 15+ min late · usually 14% 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 3934 Southwest Flight history →	STL 06:10	LAS 07:35	4%	1%	0.5%	88%
WN 2327 Southwest Flight history →	STL 09:15	LAS 10:40	8%	2%	0.5%	77%
WN 4359 Southwest Flight history →	STL 14:20	LAS 15:45	24%	6%	0.5%	59%
WN 3936 Southwest Flight history →	STL 21:55	LAS 23:25	28%	7%	0.6%	60%
F9 2017 Frontier Flight history →	STL 19:10	LAS 20:43	29%	11%	1.5%	76%
WN 3935 Southwest Flight history →	STL 19:45	LAS 21:10	31%	8%	0.6%	14%

Alternatives with one stop that day

All connections →


Southwest Details →	STL 05:35 → DEN 06:50WN 3909	50m Denver	DEN 07:40 → LAS 08:35WN 1559	5h 00m	94%	87%

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