Summer Solstice - 411
The summer solstice occurs at the moment the earth's tilt toward from the sun is at a maximum. It occurs when the sun is directly over the Tropic of Cancer, which is located at 23.5° latitude North, and runs through Southern China, Bangladesh, India, Oman, Saudi Arabia, Egypt, Bahamas, and Mexico.
For every place north of the Tropic of Cancer, the sun is at its highest point in the sky and this is the longest day of the year. During the day of the summer solstice, the sun appears at its highest elevation.
Solstices are opposite on either side of the equator, so the Summer Solstice in the Northern Hemisphere is the Winter Solstice in the Southern Hemisphere and vice versa.
The first day of each season can either be defined using astronomical events like solstices and equinoxes, or they can be determined based on meteorological factors, such as average temperatures. In the US and some Northern Hemisphere areas, the Summer Solstice marks the first day of Summer. One must know that the official date for the first day of summer may vary depending on the country's climate.
The graphic bellow ,from WRE, shows all of the seasonal changes and hours of sunlight;
Happy Summer Solstice Northern Hemisphere!