Today: WN 4673 at 07:20 is the safest bet, 9% chance of being 15+ min late; evening flights run 22–28%.

Safest bet today WN 4673 STL 07:20 → PHX 08:35 · 9% chance 15+ min late · usually 100% on time Riskiest WN 4615 STL 19:20 → PHX 20:30 · 28% chance 15+ min late · usually 40% on time

Against a calm day 17% average chance a nonstop arrives 15+ min late; 18% 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. 2 flights that already left today are not shown.


WN 4673 Southwest Flight history →	STL 07:20	PHX 08:35	9%	1%	0.2%	100%
WN 1932 Southwest	STL 09:36	PHX 10:53	11%	2%	0.2%	no record
AA 2574 American Flight history →	STL 11:03	PHX 12:46	11%	6%	0.4%	85%
AA 590 American Flight history →	STL 14:34	PHX 16:10	15%	9%	0.4%	83%
AA 3179 American Flight history →	STL 14:46	PHX 16:00	15%	9%	0.4%	68%
WN 3968 Southwest Flight history →	STL 13:20	PHX 14:30	18%	3%	0.1%	55%
WN 4112 Southwest	STL 14:06	PHX 15:30	20%	4%	0.1%	no record
WN 4114 Southwest	STL 21:50	PHX 23:05	22%	5%	0.5%	no record
WN 4113 Southwest	STL 17:50	PHX 19:05	24%	5%	0.5%	no record
WN 4615 Southwest Flight history →	STL 19:20	PHX 20:30	28%	6%	0.5%	40%

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