Aircraft and crews do not start the day at your airport
Most aircraft fly several legs in a single day, often starting that chain at a completely different airport hours earlier. A weather delay anywhere upstream in that chain arrives at your gate as a delay too, regardless of your local weather.
Crew duty-time limits compound the ripple
Flight crews have strict limits on how long they can work in a day. A delay early in their rotation can mean a crew runs out of legal flying time before reaching your flight, triggering a crew swap that adds its own delay on top of the original one.
Hub airports concentrate the effect
A weather event at a major connecting hub affects a disproportionate number of downstream flights, because so many aircraft and crews pass through that single point before fanning back out across the network.
Questions people ask
How can I tell if a delay is weather-related elsewhere?
Checking the status of the specific aircraft's previous flight, where available through flight-tracking tools, often reveals an upstream delay that local weather alone would not explain.
Do ripple delays tend to get better or worse as the day goes on?
Often worse — delays compound through the day as aircraft and crews fall further behind schedule, which is part of why early flights are statistically more likely to depart on time.