The Italian word for hail, as in pellets of frozen rain, is grandine (feminine, plural: grandini). It derives from the Latin word of the same spelling.
One way of translating the verb to hail is to use the verb cadere (to fall), as in cade la grandine (the hail falls), but it is just as common to say grandinare. Interestingly, the latter can take either avere (to have) or essere (to be) as its auxiliary verb.
È caduta tanta di quella grandine da rovinare il tetto della nostra macchina!
So much hail has fallen that it ruined the roof of our car!
A hailstorm is a grandinata whereas a hailstone is a chicco di grandine (literally ‘a grain of hail’).
In a literal and metaphorical sense, grandine can also refer to a large number of things simultaneously hurling violently through the air such as bullets (grandine di proiettili), arrows (grandine di frecce), stones (grandine di sassi) or insults (grandine di insulti). In English, the closest translations are shower or torrent.
Davanti al Palagiustizia è stato travolto da una grandine di insulti!
In front of the courthouse, he was bombarded by a shower of insults!
Finally, the expression c’è passata la grandine (lit. the hail stops by) can be used to say that something was reduced to pieces very violently and quickly or, in a playful way, to say that your hungry friends ate or drank something very quickly.