Euroclydon is a cyclonic tempestuous northeast wind which blows in the Mediterranean. It is the modern Gregalia (Gregale) or Levanter.
It may specifically refer to the name of the Gregale wind from the Adriatic Gulf, which wrecked the apostle Paul's ship on the coast of Malta on his way to Rome (Acts 27:14).
It is referenced in the second chapter of Moby-Dick.