Today looks rough: weather pushes the average chance of arriving 15+ min late to 28%, against 16% on a calm day. Safest: DL 2127 at 06:00, 17%.

Safest bet today DL 2127 IAD 06:00 → ATL 07:43 · 17% chance 15+ min late · usually 90% on time Riskiest F9 4409 IAD 20:33 → ATL 22:44 · 47% chance 15+ min late · usually 59% on time

Weather 28% 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.


DL 2127 Delta Flight history →	IAD 06:00	ATL 07:43	17%	5%	1.3%	90%
DL 1444 Delta Flight history →	IAD 12:37	ATL 14:28	22%	5%	1.2%	83%
UA 2739 United Flight history →	IAD 08:15	ATL 10:14	22%	5%	0.6%	89%worse than usual
DL 2135 Delta Flight history →	IAD 15:02	ATL 16:53	22%	6%	1.0%	73%
DL 3080 Delta Flight history →	IAD 08:27	ATL 10:18	24%	4%	0.9%	83%
UA 1357 United	IAD 22:25	ATL 00:33	25%	9%	0.8%	no record
DL 1324 Delta Flight history →	IAD 10:21	ATL 12:04	25%	4%	0.9%	85%
UA 471 United Flight history →	IAD 12:35	ATL 14:34	25%	9%	0.8%	86%worse than usual
UA 1635 United Flight history →	IAD 22:28	ATL 00:30	26%	10%	0.8%	75%
DL 1695 Delta Flight history →	IAD 17:46	ATL 19:54	28%	6%	1.2%	74%
DL 2902 Delta Flight history →	IAD 19:26	ATL 21:26	30%	6%	1.0%	78%
UA 2081 United Flight history →	IAD 17:17	ATL 19:16	35%	10%	0.7%	70%
F9 4707 Frontier Flight history →	IAD 07:49	ATL 09:59	45%	14%	1.4%	71%worse than usual
F9 4409 Frontier Flight history →	IAD 20:33	ATL 22:44	47%	25%	1.0%	59%

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