Also, Germans expected the attack further east from Normandy, at Pas de Calais..
it was the closest to England. Hitler had massive defenses in place there. While Normandy was heavily defended, it was even more heavily defended further east...we hit 'em where they were softer, during crappy, miserable weather. In fact, much of the German high command, ton include Hitler, were with family/friends/mistresses at the start of the invasion, becuase the conditions were forecasted to be so unsuitable.
One of the many miracles of Dday was the intel to know that the weather would break and allow us to get our troops there...Nothings short of God's hand!