I need historical hailstorm data for Italian cities, day by day since 2014.
I don't mind what format the data is in (csv, xml, etc...). Having a Web API would be great as well.
In the event you get no other answers (or better ones), I do have an option for you. It's a little messy and 'manual', but it will work if you have no other options.
In summary, follow these steps:
Obviously this is a little tedious. However, this site does also offer a Weather API that may or may not meet your needs.
Hopefully you find a better solution. Perhaps you could contact the Italian Meteorological Service?