Simply put, any weather will destroy your schedule. For example, last night, Chicago O’hare airport was gridlocked. Not from the cabs and buses and cars picking up and dropping off passengers, but the planes couldn’t get out fast enough. The weather comprised of many many smaller thunderstorm cells surrounding the area. It’s bad because every departure has to fly towards a specific navigation fix. So all of that departure volume has to squeeze through one of the few directions left open.
Last night, 60+ airplanes were waiting for takeoff on the taxiways and a further unknown number of planes were at the gate waiting to push back for over an hour because all of those 60+ airplanes were in the way blocking them in. Imagine going to work and backing out of your driveway was impossible because the traffic on your street was totally bumper-bumper packed up and not moving. That’s how it was.
So, an airport as busy as Chicago (ORD), Atlanta (ATL), New-york area (EWR, LGA, JFK) and especially Philadelphia (Because its runway direction launches planes directly into the NYC arrival corridor making traffic spacing a huge issue) plus a few others, will have massive problems when sometimes there’s any weather in the area. Did I mention Philly and Atlanta?
why?: Because the airport is so massive in size to handle incredible volumes of traffic in and out. When they need every single direction of the compass to direct departures and arrivals to and from, anything in the way begins delays. On a normal sunny day, during rush hour (the big push) It’s not uncommon to be 10 or 20 in line for departure. On a nice day.
solution: Honestly, just travel in the mornings. Don’t wait until the afternoon and especially during seasonal change times, summer into fall, winter into spring, etc. Every three months when seasons change there’s a couple of volatile weeks. rain storms, even serious morning fog can absolutely stop Chicago in the mornings. Would you rather be delayed at the airport all day with multiple chances to get to your destination or at night falling off your feet tired with that only one chance to get out and it cancels for the weather? now you sleep at the airport.
Just a note about how it works. Plan ahead. If weather cancels the plane, the Airline will not pay for a hotel or food. It’s mother nature at work and they can’t control it. You chose to fly on a crap weather day, just like choosing to drive during a tornado. Don’t be surprised if it’s not a smooth experience.