Today looks like a normal day here: all 3 nonstops are 21–24% likely to arrive 15+ min late.

Safest bet today WN 3992 STS 15:55 → LAS 17:40 · 21% chance 15+ min late · usually 63% on time Riskiest AS 554 STS 14:00 → LAS 15:42 · 24% chance 15+ min late

Against a calm day 22% average chance a nonstop arrives 15+ min late; 15% 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. Dimmed: airlines we don’t forecast yet, shown with their 12-month record if they usually fly that weekday.


WN 3992 Southwest Flight history →	STS 15:55	LAS 17:40	21%	7%	0.2%	63%
WN 4723 Southwest	STS 15:10	LAS 16:52	22%	6%	0.2%	no record
AS 554 Alaska	STS 14:00	LAS 15:42	24%	7%	1.0%	no record
AS 2459 Alaska flown by Horizon no forecast: 12-month record	STS 13:06	LAS 14:44	8%	2%	0.0%	92%

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