Vatican City is a city state that came into existence in 1929. It is therefore to be clearly distinguished from the Holy See, which already was in existence for many centuries before that date.
The Vatican climate is the same as Rome's; a temperate, Mediterranean climate with mild, rainy winters from September to mid-May and hot, dry summers from May to August.
The Vatican Christmas Tree, also called the Saint Peter's Square Christmas Tree, is the decorated tree that is erected annually in the Saint Peter's Square directly in front of St. Peter's Basilica in the Vatican City to celebrate the Christmas holiday season.