Because of the way the Earth rotates during the summer months, the Earth is closer to the sun, resulting in longer daylight hours. Northern cities have longer daylight hours than those at lower latitudes.
Cities around the world at lower latitudes may have less daylight hours, but the sun's heat and brightness is more intense. This causes higher temperatures and a greater risk of sunburn to those outdoors during the daylight hours.
During the summer, the continental U.S. averages between 14 and 16 hours of daylight every day. Northern cities around the world such as Tokyo or London often have 16 hours of daylight. As the Earth continues its rotation, after the summer solstice, the days become shorter in the Northern Hemisphere and longer in the Southern Hemisphere.