Today looks like a normal day here: all 4 nonstops are 18–26% likely to arrive 15+ min late.

Safest bet today WN 1417 SFO 10:50 → STL 16:55 · 18% chance 15+ min late · usually 23% on time Riskiest WN 3257 SFO 13:05 → STL 18:58 · 26% chance 15+ min late

Against a calm day 22% average chance a nonstop arrives 15+ min late; 31% for the same flights on a calm-weather day

Every nonstop today

12-month record →

Ranked by the chance of arriving 15+ minutes late, 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.


WN 1417 Southwest Flight history →	SFO 10:50	STL 16:55	18%	4%	0.1%	23%
UA 2090 United Flight history →	SFO 12:12	STL 18:17	21%	5%	0.1%	75%
UA 1905 United	SFO 12:40	STL 18:40	22%	5%	0.1%	no record
WN 3257 Southwest	SFO 13:05	STL 18:58	26%	5%	0.1%	no record

How these are worked out. Each flight’s odds are our forecast for that day; 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 Mon, Oct 5 (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