Today: WN 3280 at 10:47 is the safest bet, 10% chance of being 15+ min late; evening flights run 25–38%.

Safest bet today WN 3280 ONT 10:47 → SJC 12:14 · 10% chance 15+ min late Riskiest WN 3845 ONT 16:35 → SJC 17:45 · 38% chance 15+ min late · usually 70% on time

Against a calm day 25% 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. 2 flights that already left today are not shown.


WN 3280 Southwest	ONT 10:47	SJC 12:14	10%	4%	0.1%	no record
WN 2433 Southwest	ONT 12:55	SJC 14:05	21%	6%	0.1%	no record
WN 3282 Southwest	ONT 20:35	SJC 22:02	25%	9%	0.5%	no record
WN 4020 Southwest	ONT 15:50	SJC 17:17	26%	10%	0.1%	no record
WN 3164 Southwest Flight history →	ONT 21:30	SJC 22:45	27%	11%	0.5%	65%
WN 3845 Southwest Flight history →	ONT 16:35	SJC 17:45	38%	11%	0.2%	70%

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 Sun, Oct 4 (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