Excerpts are from an article which appeared in The Points Guy.
The table below provides a proxy for total weather delays, measured in minutes, for the period between October 2017 and October 2018. It includes delays to the National Aviation System that are not strictly weather-related, such as traffic pileups at the major hubs and late-arriving aircraft that may not be due to weather, but it excludes maintenance issues or airline-controlled delays. What we know is that between 50-60% of NAS delays are due to weather — but not extreme weather — and that airline-controlled delays represent less than 5% of the total.
Worst US Airports for Weather Measured in Delay Minutes
| AIRPORT | NATIONAL AVIATION SYSTEM DELAYS | EXTREME WEATHER DELAYS | LATE-ARRIVING AIRCRAFT DELAYS | ||
| Chicago O’Hare (ORD) | 1,707,353 | 270,189 | 1,867,386 | ||
| Hartsfield-Jackson Atlanta (ATL) | 986,176 | 263,847 | 1,514,276 | ||
| Newark Liberty (EWR) | 1,888,390 | 114,335 | 732,926 | ||
| Dallas/Fort Worth (DFW) | 815,032 | 234,693 | 1,456,957 | ||
| San Francisco (SFO) | 1,435,733 | 101,105 | 936,938 | ||
| LaGuardia (LGA) | 1,207,991 | 169,228 | 807,517 | ||
| Denver (DEN) | 527,483 | 108,565 | 1,159,518 | ||
| Boston Logan (BOS) | 756,415 | 92,246 | 923,118 | ||
| New York JFK | 825,634 | 98,234 | 705,328 |
Source: Bureau of Transportation Statistics, Weather Delays by Airport for the period from October 2017 to October 2018
So…what does this tell you?
You probably already know Chicago O’Hare is to be avoided in the winter. Atlanta is affected by weather as well. In fact, it’s 32% worse for delays due to system delays and thunderstorms.
Dallas/Fort Worth, American’s major hub, is also affected by thunderstorms.
San Francisco has fog. And, they have two parallel runways separated by only 750 feet. In good visibility…not a problem. In poor weather conditions FAA regulations do not permit aircraft to land side by side unless the runways are separated by 4,300 feet. According to SFO, this reduces operations by half during poor weather.