Why not "Siamo in settembre?" Also, is the capitalisation of the names of the month unimportant, unlike English?
Wouldn't it be a better (not more literal) transaltion if it were "It is September"?
I asked my Italian friend and she said that 'in settembre' is ok but not normally used. She said that it sounds strange and kind of archaic. She suggested to me that I always use 'a settembre'
Nobody knows if we can say siamo in settembre? or why is a used here instead of in?
That's correct. In fact, English is the only language that I know of that capitalizes months' names.