Today: WN 3165 at 06:00 is the safest bet, 2% chance of being 15+ min late; evening flights run 17–19%.

Safest bet today WN 3165 ONT 06:00 → SMF 07:25 · 2% chance 15+ min late · usually 97% on time Riskiest WN 3289 ONT 20:55 → SMF 22:28 · 19% chance 15+ min late

Against a calm day 13% average chance a nonstop arrives 15+ min late; 10% 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 3165 Southwest Flight history →	ONT 06:00	SMF 07:25	2%	1%	0.4%	97%
WN 3283 Southwest	ONT 06:23	SMF 07:55	2%	1%	0.4%	no record
WN 3166 Southwest Flight history →	ONT 09:45	SMF 11:10	8%	2%	0.4%	91%
WN 956 Southwest	ONT 09:45	SMF 11:17	8%	2%	0.4%	no record
WN 1274 Southwest	ONT 12:00	SMF 13:32	15%	3%	0.3%	no record
WN 670 Southwest Flight history →	ONT 15:40	SMF 17:05	15%	5%	0.5%	71%
WN 3167 Southwest Flight history →	ONT 12:00	SMF 13:20	15%	3%	0.3%	92%
WN 1272 Southwest	ONT 13:50	SMF 15:22	16%	4%	0.3%	no record
WN 2298 Southwest Flight history →	ONT 13:20	SMF 14:40	16%	4%	0.3%	88%
WN 235 Southwest	ONT 16:25	SMF 17:58	17%	6%	0.5%	no record
WN 3170 Southwest Flight history →	ONT 18:30	SMF 19:55	18%	6%	0.5%	74%
WN 855 Southwest	ONT 18:15	SMF 19:47	18%	6%	0.5%	no record
WN 208 Southwest Flight history →	ONT 20:50	SMF 22:15	19%	7%	0.5%	69%
WN 3289 Southwest	ONT 20:55	SMF 22:28	19%	7%	0.5%	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 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