The midpoint of a standard 365-day calendar year occurs on July 2, which is the 183rd day of the year. July 1 marks the midpoint of a leap year, which is 366 days long.
The exact midpoint of a year of either duration occurs at noon on the given day. This does not account for the fact that the Western, or Gregorian, calendar, which is based on the movement of the sun, has a year that is slightly longer than 365 days but shorter than 366 days. July 1 or July 2 is merely midyear according to this calendar. The lunar calendar year only consists of 354 days.