Friday, October 9 · typical odds for a Friday (too early for a weather forecast) · issued Sun 4:00 PM ET · 5 nonstops

Fri, Oct 9: AA 3814 at 09:39 is the safest bet, 12% chance of being 15+ min late; evening flights run 19–34%.

Safest bet that day AA 3814 STL 09:39 → BOS 13:24 · 12% chance 15+ min late · usually 90% on time Riskiest WN 4724 STL 19:55 → BOS 23:30 · 34% chance 15+ min late · usually 61% 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.


AA 3814 American flown by Envoy Flight history →	STL 09:39	BOS 13:24	12%	4%	0.7%	90%
WN 3891 Southwest Flight history →	STL 09:55	BOS 13:30	14%	3%	0.5%	82%
AA 4678 American flown by Republic Flight history →	STL 19:51	BOS 23:37	19%	7%	0.8%	59%
WN 3892 Southwest Flight history →	STL 14:30	BOS 18:05	32%	9%	0.5%	38%
WN 4724 Southwest Flight history →	STL 19:55	BOS 23:30	34%	8%	0.5%	61%

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