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: UA 3552 at 10:00 is the safest bet, 7% chance of being 15+ min late; evening flights run 15–27%.

Safest bet that day UA 3552 IAD 10:00 → BOS 11:52 · 7% chance 15+ min late · usually 85% on time Riskiest UA 688 IAD 17:25 → BOS 19:14 · 27% chance 15+ min late · usually 63% 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.


UA 3552 United flown by Republic Flight history →	IAD 10:00	BOS 11:52	7%	3%	0.8%	85%
UA 641 United Flight history →	IAD 08:35	BOS 10:20	8%	3%	0.6%	92%
UA 3615 United flown by Republic Flight history →	IAD 15:30	BOS 17:24	14%	6%	0.8%	65%
UA 755 United Flight history →	IAD 22:10	BOS 23:59	15%	5%	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	27%	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 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