Learn Italian: State per partire? Sta per nevicare! - Are you all about to leave? It's about to snow!

Stare per is used to describe an action that is just about to happen. You conjugate the verb stare to match the subject (like state for 'you all' or sta for 'it'), add the word per, and then leave the main action verb in its dictionary form (the infinitive), like partire (to leave) or nevicare (to snow).

Why do we use State in the first question and Sta in the second sentence?

The verb stare changes based on who is doing the action. State is the 'you all' (voi) form, so the first sentence asks 'Are you all about to leave?'. Sta is the 'it' (lui/lei) form. We use it in the second sentence because weather events like snowing use an impersonal 'it' subject ('It is about to snow').

Could I use uscire instead of partire here?

It depends on what kind of leaving you mean. Partire is usually used for departing on a trip or a journey. If you were just asking if someone was about to leave the house or a room to go outside, you would use uscire (State per uscire?).

Do weather verbs like nevicare always take the sta form?