Rule reminder
Italian has specific impersonal weather verbs used only in 3rd person singular: piove (it's raining) from piovere, nevica (it's snowing) from nevicare, grandina (it's hailing) from grandinare, tuona (it's thundering) from tuonare, lampeggia (there's lightning) from lampeggiare.
Come si dice 'It's raining'?