What does Dudley feel in this passage? I thought that he could feel a chill and got scared too.
But then again, there is still the point that Mrs. Figg was able to 'sense' the presence of the Dementors in OotP, even if it isn't clear if she could see them for herself.
But something else I wonder about this. Would a Muggle notice the chill in the air and the sudden unhappiness that comes with the presence of the Dementors? Maybe it is just that Mrs. Figg felt these things and was just aware of what they meant.