Today: WN 3760 at 05:40 is the safest bet, 4% chance of being 15+ min late; evening flights run 18–20%.

Safest bet today WN 3760 SMF 05:40 → BOI 08:05 · 4% chance 15+ min late · usually 100% on time Riskiest WN 2515 SMF 14:15 → BOI 16:52 · 21% chance 15+ min late

Against a calm day 15% average chance a nonstop arrives 15+ min late; 13% 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. Dimmed: airlines we don’t forecast yet, shown with their 12-month record if they usually fly that weekday.


WN 3760 Southwest Flight history →	SMF 05:40	BOI 08:05	4%	1%	0.2%	100%
WN 3896 Southwest	SMF 07:40	BOI 10:17	6%	1%	0.2%	no record
WN 3587 Southwest	SMF 21:40	BOI 00:17	18%	3%	0.5%	no record
WN 418 Southwest Flight history →	SMF 13:20	BOI 15:45	19%	3%	0.1%	55%
WN 3762 Southwest Flight history →	SMF 21:50	BOI 00:20	20%	3%	0.5%	75%
WN 2515 Southwest	SMF 14:15	BOI 16:52	21%	3%	0.1%	no record
AS 2157 Alaska flown by Horizon no forecast: 12-month record	SMF 13:10	BOI 15:35	7%	2%	1.5%	93%

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