Summer is one of the four temperate seasons. It is associated with hot and often dry weather. In many countries it is the time of school and university holidays.
Different definitions of the start and end days exist. In astronomy, summer begins with the summer solstice (around 21 June in the Northern hemisphere, and 21 December in the Southern hemisphere) and ends with the autumn equinox (around 21 September in the Northern hemisphere and 21 March in the Southern hemisphere).
In meteorology, summer is defined by convention as the whole months of June, July and August in the Northern hemisphere and the whole months of December, January and February in the Southern hemisphere.