The Surprising Blunders English Speakers Make Wishing Someone Happy New Year in Italian
English compresses the entire late-December transition into the catch-all terms "New Year's Eve" and "New Year's Day." Italian maintains a strict division anchored in the liturgical calendar. Conflating the evening celebration with the calendar holiday reveals a fundamental gap in Italian holiday greetings.
December 31 is universally recognized as La Notte di San Silvestro, named for Saint Sylvester, the fourth-century pope whose feast day falls on the final date of the Gregorian year. If an Italian invites you out on the thirty-first, they will ask about your plans for San Silvestro. Conversely, Capodanno translates literally to the "head of the year" and denotes exclusively January 1.
When locals attend the massive evening feast on December 31, they gather for the Cenone di Capodanno, literally the "great dinner of New Year's", because the meal bridges midnight into the nascent year. Using Capodanno to describe what you did at 9:00 PM on December 31 sounds premature to native ears. You spent the evening celebrating San Silvestro, drank a midnight toast to inaugurate Capodanno, and then woke up to the actual public holiday.