In Chicago, there are 15:02 hours of daylight on the summer solstice of June 21, 1999. The above plots show how the date of the summer solstice shifts through the Gregorian calendar according to the insertion of leap years. The table below gives the universal time of the summer solstice. To convert to U. S. Eastern daylight saving time, subtract 4 hours, so the summer solstice occurs on June 21, 1998 at 10:00 a.m. EDT; June 21, 1999 at 15:47 (3:46 p.m.) EDT; and June 20, 2000 at 21:36 (9:36 p.m.) EDT.