Today looks like a normal day here: all 8 nonstops are 13–21% likely to arrive 15+ min late.

Safest bet today WN 3877 STL 12:07 → PHX 13:40 · 13% chance 15+ min late Riskiest WN 4113 STL 16:55 → PHX 18:16 · 21% chance 15+ min late

Against a calm day 16% average chance a nonstop arrives 15+ min late; 16% 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. 3 flights that already left today are not shown.


WN 3877 Southwest	STL 12:07	PHX 13:40	13%	2%	0.1%	no record
WN 3878 Southwest	STL 20:42	PHX 22:07	15%	4%	0.5%	no record
WN 4114 Southwest	STL 20:50	PHX 22:18	15%	3%	0.5%	no record
WN 437 Southwest	STL 12:10	PHX 13:30	15%	2%	0.1%	no record
AA 590 American Flight history →	STL 14:37	PHX 16:23	15%	4%	0.2%	83%
WN 1587 Southwest	STL 17:05	PHX 18:44	18%	3%	0.1%	no record
AA 2660 American	STL 18:11	PHX 19:57	20%	6%	0.3%	no record
WN 4113 Southwest	STL 16:55	PHX 18:16	21%	3%	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 Tue, Oct 6 (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