Is hail a proper noun

No, the noun 'hail' is a common noun, a general Word for pieces of ice that fall from clouds like rain.

A proper noun is the name or title of a specific person, a place, or a thing; for example, the Hail & Hog Kitchen and Tap in Ashburn VA or "Hail to the Chief", the official Presidential Anthem of the United States.

The Word 'hail' is also a verb: hail, hails, hailing, hailed.