I was dealing with delays and eventual cancelation with AA over the weekend. They also cited weather in Miami which is an interesting argument to attempt when my flight tracker showed all kinds of flights departing Miami and only a weak stormfront in the Florida strait.
If it is weather, the airlines don’t have to pay for the forced layover if it goes over night.
So no matter what, if there is a lot of cancelations it is weather. A reason I always pack a few days worth of extra clothes.