Monday, October 5 · our forecast odds · issued Sun 9:00 PM ET · 10 nonstops

Tomorrow: WN 4122 at 07:35 is the safest bet, 8% chance of being 15+ min late; evening flights run 20–23%.

Safest bet that day WN 4122 MDW 07:35 → PHL 10:35 · 8% chance 15+ min late · usually 94% on time Riskiest WN 4263 MDW 18:55 → PHL 21:55 · 23% chance 15+ min late · usually 51% on time

Against a calm day 17% average chance a nonstop arrives 15+ min late; 15% for the same flights on a calm-weather day

Every nonstop on Mon, Oct 5

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 4122 Southwest Flight history →	MDW 07:35	PHL 10:35	8%	1%	0.4%	94%
WN 2057 Southwest	MDW 07:50	PHL 10:59	8%	2%	0.4%	no record
WN 4901 Southwest Flight history →	MDW 09:00	PHL 11:55	11%	2%	0.5%	96%
WN 3266 Southwest	MDW 11:45	PHL 14:54	15%	3%	0.6%	no record
WN 2953 Southwest	MDW 13:30	PHL 16:39	18%	3%	0.6%	no record
WN 4351 Southwest Flight history →	MDW 13:40	PHL 16:45	19%	4%	0.6%	57%
WN 4757 Southwest	MDW 18:55	PHL 22:04	20%	5%	0.6%	no record
WN 2954 Southwest	MDW 16:40	PHL 19:49	22%	5%	0.6%	no record
WN 4948 Southwest Flight history →	MDW 15:20	PHL 18:20	22%	5%	0.6%	60%
WN 4263 Southwest Flight history →	MDW 18:55	PHL 21:55	23%	5%	0.6%	51%

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