Today: only flights still to leave (it’s 5:09 pm at San Francisco); 16 already left

Sunday, October 4 · our forecast odds · issued Sun 6:00 PM ET · 4 nonstops

Today looks rough: weather pushes the average chance of arriving 15+ min late to 40%, against 23% on a calm day. Safest: UA 796 at 21:25, 36%.

Safest bet today UA 796 SFO 21:25 → BOS 06:21 · 36% chance 15+ min late · usually 87% on time Riskiest B6 134 SFO 21:44 → BOS 06:28 · 49% chance 15+ min late · usually 65% on time

Weather 40% average chance a nonstop arrives 15+ min late; 23% 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. 16 flights that already left today are not shown.


UA 796 United Flight history →	SFO 21:25	BOS 06:21	36%	11%	0.6%	87%worse than usual
DL 1655 Delta Flight history →	SFO 22:10	BOS 06:45	36%	14%	0.7%	69%
UA 1665 United Flight history →	SFO 23:05	BOS 08:01	40%	12%	0.6%	84%worse than usual
B6 134 JetBlue Flight history →	SFO 21:44	BOS 06:28	49%	22%	0.7%	65%worse than usual

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