Scottish: habitational name from a place called Wedale (now Stow) near Edinburgh. The origins of this place name are uncertain. The second element is evidently Old English dæl or Old Norse dalr ‘valley’. The first element might be Old English wedd ‘pledge’, ‘security’ or its Old Norse cognate veð (although this is not found elsewhere as a place name element).
Dictionary of American Family Names, Oxford University Press, Mar 2003