Hello. I could download the add-on from first link; i.e.:
http://www.nvda.it/files/plugin/weather_plus4.5.nvda-addon
I recieved a zip file, then renamed the .zip to .nvda-addon, and ran
it to update my installed copy.
Dear Adriano, would you please correct the "Check for update" system
in the next release?
Thanks for your great work.

--
Best wishes,
Mohammadreza Rashad