Friday, October 9 · typical odds for a Friday (too early for a weather forecast) · issued Mon 12:00 PM ET · 4 nonstops

Fri, Oct 9: UA 2637 at 09:58 is the safest bet, 11% chance of being 15+ min late; the others run 21–25%.

Safest bet that day UA 2637 DEN 09:58 → GRR 14:35 · 11% chance 15+ min late · usually 88% on time Riskiest WN 1539 DEN 13:00 → GRR 17:20 · 25% chance 15+ min late · usually 58% 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 2637 United Flight history →	DEN 09:58	GRR 14:35	11%	3%	0.5%	88%
UA 2121 United Flight history →	DEN 17:55	GRR 22:35	21%	8%	0.5%	71%
F9 1248 Frontier Flight history →	DEN 15:08	GRR 19:40	23%	7%	0.6%	89%worse than usual
WN 1539 Southwest Flight history →	DEN 13:00	GRR 17:20	25%	5%	0.5%	58%

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