This is nothing except an interesting point between North and South pronunciation "One of the most well-known examples is the difference in thepronunciation of the letter s when it occurs between two vowels. Inthe North, it is usually pronounced /z/, while in the southern-central regions it is pronounced /s/." http://www.thepolyglotdream.com/italy-languages-dialects-accents/
I had an italian explain it to me: You usually salute buona sera/buon giorno when you arrive, and buona serata, buona giornata when you go. The meaning of the first being the wish for a "whole" good day or evening and the meaning of the later being "buon (proseguimento di) giornata", o "buon (proseguimento di) giornata", that is have a good what is left of the day or of the evening.
good evening = buonasera
good afternoon = buon pomeriggio
- buongiorno (from 5.00am to 5.00pm)
- buon pomeriggio (it is said around noon to wish a good afternoon)
- buonasera (from 5.00pm to midnight and beyond)
- buonanotte (You say "buonanotte" to someone late at night before you or someone else goes to sleep)
(formally) "buongiorno" and "buonasera" cover all day
(informally) "ciao" cover all day
You can use buongiorno, buonasera, ciao when you arrive and when you leave.
You can use buon pomeriggio, buonanotte when you or someone else leaves
Best American English translation: Good evening. Both "buonasera" and "good evening" are used as greetings, i.e. when you are meeting someone. The English "good night" is usually as you're departing or preparing to sleep. Granted, there's no exact boundary between afternoon and evening.
In my opinion, it is: both "good night" and "buona notte" tend to imply that you're going to sleep.
The problem is that while that's automatic in Italian, there is a rare and probably outdated usage of "good night" as a greeting: "a conventional expression of farewell, or, rarely, of greeting, used in the late afternoon, the evening, or at night, esp when departing to bed" (quote from the Collins dictionary).
According to this definition "good night" could be synonymous with "good evening"; however, I've never heard it used this way, and I'd really like to hear a few native speakers confirm it before adding it as a possible translation.