Friday, October 9 · typical odds for a Friday (too early for a weather forecast) · issued Mon 12:00 PM ET · 12 nonstops

Fri, Oct 9: WN 3909 at 05:35 is the safest bet, 3% chance of being 15+ min late; evening flights run 21–27%.

Safest bet that day WN 3909 STL 05:35 → DEN 06:50 · 3% chance 15+ min late · usually 91% on time Riskiest WN 3913 STL 18:40 → DEN 20:00 · 27% chance 15+ min late · usually 47% 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 3909 Southwest Flight history →	STL 05:35	DEN 06:50	3%	1%	0.5%	91%
UA 362 United Flight history →	STL 05:10	DEN 06:32	4%	2%	0.5%	91%
UA 2459 United Flight history →	STL 09:06	DEN 10:30	8%	3%	0.5%	92%
WN 3910 Southwest Flight history →	STL 09:25	DEN 10:40	9%	2%	0.5%	90%
UA 1380 United Flight history →	STL 13:38	DEN 15:00	14%	6%	0.5%	86%
WN 4312 Southwest Flight history →	STL 11:30	DEN 12:40	15%	3%	0.5%	72%
WN 824 Southwest Flight history →	STL 13:55	DEN 15:10	19%	5%	0.5%	60%
F9 4567 Frontier Flight history →	STL 20:08	DEN 21:44	21%	7%	0.8%	76%
UA 1483 United Flight history →	STL 16:48	DEN 18:23	22%	7%	0.5%	56%
WN 3914 Southwest Flight history →	STL 22:35	DEN 23:55	23%	5%	0.5%	60%
WN 3912 Southwest Flight history →	STL 16:00	DEN 17:20	26%	6%	0.5%	51%
WN 3913 Southwest Flight history →	STL 18:40	DEN 20:00	27%	6%	0.5%	47%

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