Originally Posted by
cfischer
They will do it with maintenance issues or other controllable events.
Unfortunately for the OP, this one is being called weather/ATC. (UA2072 is the only EWR-TPA canceled at the moment)
Your flight is canceled because of current or anticipated disruptions related to airspace and/or ground congestion. Your safety is our priority and we're sorry for the inconvenience.
There is an airspace flow program in effect for all southbound flights crossing over/near North Florida, as has become somewhat common.