On 2026-09-04, 25 airports across the United States were affected by 39 separate delay programmes according to FAA data tracked by travelandtournews.com. Chicago O’Hare International (ORD) was the worst hit airport, enduring ground stop programmes due to thunderstorms and wind lasting 6 hours and 40 minutes.
Delay Programmes by Airport and Type
The 39 programmes included 12 Ground Stop Programs, which hold departures at their origin airports; 6 Ground Delay Programs, that meter arrivals with later departure times; and 21 General Arrival/Departure Delay Info advisories. The longest single programme was a Ground Delay Program at Boston Logan International (BOS), running for 22 hours, with a peak average delay of 136 minutes and a peak maximum delay of 239 minutes.
Chicago O’Hare (ORD) had both a Ground Stop and Ground Delay program due to thunderstorms and wind from 13:00 to 19:40 UTC, totaling 6 hours and 40 minutes for the stop and an
additional 4 hours 20 minutes for the delay program. Other airports with ground stops mostly faced thunderstorms, including Ronald Reagan Washington National (DCA) with a 3 hour 20 minute stop, Orlando International (MCO) for 3 hours, and Detroit Metropolitan (DTW) for 2 hours 40 minutes.
LaGuardia (LGA) had overlapping Ground Stop, Ground Delay, and General Delay programmes throughout the day, with peak delays up to 139 minutes under stops and 91 average minutes in the delay advisory programmes. San Diego International (SAN) experienced a 22-hour Ground Delay Program caused by airport volume, alongside a short 20-minute ground stop for security
reasons.
| Airport | FAA programme | Cause | Peak average delay | In force (UTC) |
|---|---|---|---|---|
| Chicago O’Hare International (ORD) | Ground Stop Programs | thunderstorms; wind | – | 13:00 to 19:40 (6 hours 40 minutes) |
| Ronald Reagan Washington National (DCA) | Ground Stop Programs | thunderstorms | – | 18:40 to 22:00 (3 hours 20 minutes) |
| Orlando International (MCO) | Ground Stop Programs | thunderstorms | – | 19:00 to 22:00 (3 hours) |
| Detroit Metropolitan Wayne County (DTW) | Ground Stop Programs | thunderstorms; THUNDERSTORMS | – | 13:20 to 16:00 (2 hours 40 minutes) |
| Washington Dulles International (IAD) | Ground Stop Programs | thunderstorms | – | 19:20 to 22:00 (2 hours 40 minutes) |
| LaGuardia (LGA) | Ground Stop Programs | THUNDERSTORMS; thunderstorms | – | 19:20 to 22:00 (2 hours 40 minutes) |
| Pittsburgh International (PIT) | Ground Stop Programs | thunderstorms | – | 00:00 to 01:00 (1 hour) |
| YYZ | Ground Stop Programs | airspace volume | – | 18:00 to 18:40 (40 minutes) |
| Fort Lauderdale-Hollywood International (FLL) | Ground Stop Programs | thunderstorms | – | 13:20 to 13:40 (20 minutes) |
| Tampa International (TPA) | Ground Stop Programs | thunderstorms | – | 19:20 to 19:40 (20 minutes) |
| Baltimore/Washington International (BWI) | Ground Stop Programs | thunderstorms | – | 20:20 to 20:40 (20 minutes) |
| San Diego International (SAN) | Ground Stop Programs | security | – | 21:40 to 22:00 (20 minutes) |
| Boston Logan International (BOS) | Ground Delay Programs | low ceilings; runway construction | 136 min | 00:00 to 22:00 (22 hours) |
| LaGuardia (LGA) | Ground Delay Programs | thunderstorms | 79 min | 00:00 to 22:00 (22 hours) |
Thunderstorms and Weather Drove Most Delay Programmes
The dominant causes for the delay programmes cited by the FAA were weather-related: various entries relating to thunderstorms appeared 154 times in total when including “thunderstorms”, “WX:Thunderstorms”, and uppercase variants. These weather issues accounted for the majority of Ground Stops and Ground Delay Programs.
Other notable causes included airport volume, cited 40 times, and runway construction, cited 28 times, both primarily driving Ground Delay Programs. The FAA also listed traffic management initiatives designated “TM Initiatives:SWAP:WX” frequently, present in 85 samples across general delay info programmes.
Comparison with Yesterday and Recent Averages
The number of airports affected (25) on 2026-09-04 was slightly below yesterday’s count of
26, and slightly above the seven-day average of 19.7 airports affected. The total programmes (39) dropped by 2 compared to 41 yesterday. This day was not the worst within the recent tracking window.
Methodology. travelandtournews.com samples the FAA’s National Airspace System status feed every 20 minutes throughout the US operating day and aggregates the result. This report is built from 52 samples taken between 00:00 and 22:00 UTC on 2026-09-04. Durations are the observed window between the first and last sample in which a programme was in force, so a programme’s true length may be slightly longer than shown. Ground
stops, ground delay programmes, airport closures and general delays are all published by the FAA in real time; the daily aggregation is ours.
