Ryanair has confirmed that thunderstorms in Stansted today have led to a number of flights being cancelled. Customers who are affected will be contacted by email or text message.
Additionally, German, French, Greek and Croatian air traffic control strikes have caused delays to 441 flights.
Stansted and ATC Update - July 31st: pic.twitter.com/tkocR0bZIu
— Ryanair (@Ryanair) July 31, 2018
More information can be found here.