Flights can be canceled due to a variety of reasons. This may include bad weather, such as strong winds, heavy rain, fog, or snow. Mechanical issues, such as aircraft maintenance, and air traffic congestion, can also cause flights to be canceled. Flight crews might be running late due to other delays, or the airline might be overbooked and have to reallocate seats. In rare cases, a flight cancellation can also be due to safety or security issues.