When you first got your budgies your father was agreeable to them I presume? What has happened to change his mind?
I had a huge heavy cage under a veranda and hawks still got to my birds. It was very sad and my budgie died.
Your cage can be pushed or pulled over or even be lifted in to the air. The stress and fright can kill your budgies without the actual attack.
I am not trying to be horrible but please try your hardest to find them somewhere safe as possible. The heat will also be a factor as they are used to be inside.