Today: WN 1103 at 17:05 is the safest bet, 23% chance of being 15+ min late; morning flights run 25–26%.

Safest bet today WN 1103 BWI 17:05 → SJU 21:15 · 23% chance 15+ min late · usually 55% on time Riskiest F9 1774 BWI 12:35 → SJU 16:40 · 44% chance 15+ min late · usually 54% on time

Against a calm day 29% average chance a nonstop arrives 15+ min late; 19% 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 1103 Southwest Flight history →	BWI 17:05	SJU 21:15	23%	6%	0.6%	55%
WN 4443 Southwest Flight history →	BWI 08:10	SJU 12:25	25%	3%	0.2%	75%
WN 4510 Southwest	BWI 08:14	SJU 12:25	26%	3%	0.2%	no record
WN 1164 Southwest	BWI 20:01	SJU 00:16	27%	6%	0.6%	no record
WN 1104 Southwest Flight history →	BWI 20:10	SJU 00:20	28%	6%	0.6%	46%
F9 1774 Frontier Flight history →	BWI 12:35	SJU 16:40	44%	11%	1.8%	54%

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