In the Northern Hemisphere, the official summer season begins with the June solstice, which takes place on June 20th, 21st or 22nd each year, and ends with the September equinox, which takes place on September 22nd or 23rd each year; the exact duration of summer depends on when the solstice and equinox will take place and can range from 92 to 95 days. Though summer is associated with warm temperatures and the concept of 'summer break' for students, the season has an official scientific definition, as is defined above. Summer weather in the Northern Hemisphere may begin before the official start of the season and last until after fall has begun with the advent of the September equinox.
While it is officially summer in the Northern Hemisphere, it is winter in the Southern Hemisphere; the exact duration of summer may differ in the Southern Hemisphere. The June solstice marks the longest day and shortest night of the year, marking the extended hours of daylight that characterize summer in the Northern Hemisphere. This is caused by the fact that the Earth is tilted on its axis in such a way as to allow maximum exposure to the sun in the Northern Hemisphere, leading to warmer temperatures and longer days.