Thursday, October 8 · typical odds for a Thursday (too early for a weather forecast) · issued Sun 12:00 PM ET · 4 nonstops

Thu, Oct 8: UA 641 at 08:35 is the safest bet, 11% chance of being 15+ min late; the others run 24–36%.

Safest bet that day UA 641 IAD 08:35 → BOS 10:20 · 11% chance 15+ min late · usually 92% on time Riskiest UA 688 IAD 17:25 → BOS 19:14 · 36% chance 15+ min late · usually 63% on time

Every nonstop on Thu, Oct 8

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.


UA 641 United Flight history →	IAD 08:35	BOS 10:20	11%	5%	0.9%	92%
UA 1392 United Flight history →	IAD 12:55	BOS 14:40	24%	12%	0.7%	82%
YX 3503 Republic	IAD 15:09	BOS 16:55	27%	10%	1.0%	no record
UA 688 United Flight history →	IAD 17:25	BOS 19:14	36%	15%	0.7%	63%

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 Thu, Oct 8 (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