Saturday, October 10 · typical odds for a Saturday (too early for a weather forecast) · issued Sun 8:00 PM ET · 4 nonstops

Sat, Oct 10: UA 641 at 08:35 is the safest bet, 8% chance of being 15+ min late; evening flights run 16–32%.

Safest bet that day UA 641 IAD 08:35 → BOS 10:20 · 8% chance 15+ min late · usually 92% on time Riskiest UA 688 IAD 17:25 → BOS 19:14 · 32% chance 15+ min late · usually 63% on time

Every nonstop on Sat, Oct 10

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	8%	3%	0.6%	92%
UA 755 United Flight history →	IAD 22:10	BOS 23:59	16%	6%	0.6%	81%
UA 1392 United Flight history →	IAD 12:55	BOS 14:40	18%	7%	0.6%	82%
UA 688 United Flight history →	IAD 17:25	BOS 19:14	32%	12%	0.6%	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 Sat, Oct 10 (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