this day is the first day of the last third of the year as well as the two thirds point of the common year because there are 243 days before and 121 days after it in common years. there are 244 days before and 121 after it in leap years. the exact time the second third of the year starts is 8:00 a.m. in countries that use summer time the actual exact time of the midpoint in a common year is at 9:00 a.m. for locations in the northern hemisphere, or 7:00 a.m. for locations in the southern hemisphere; this is when 243 days and 8 hours have elapsed and there are 121 days and 16 hours remaining. in a leap year in those countries, the last third of the year starts at midnight. in countries that use summer time, the second third starts at 1:00 a.m. on september, or 11:00 p.m. on august 31 in the southern hemisphere. this is due to summer time having advanced the time by one hour.