Summer is the warmest of the four temperate seasons, between spring and autumn. At the summer solstice, the days are longest and the nights are shortest, with day-length decreasing as the season progresses after the solstice. The date of the beginning of summer varies according to climate, culture and tradition, but when it is summer in the Northern Hemisphere it is winter in the Southern Hemisphere and vice versa.
Summer is traditionally associated with hot dry weather, but this does not occur in all regions. In areas of the tropics and subtropics, the wet season occurs during the summer. The wet season is the main period of vegetation growth within the savanna climate regime. Where the wet season is associated with a seasonal shift in the prevailing winds, it is known as a monsoon.