Summer

From an astronomical view, the equinoxes and solstices would be the middle of the respective seasons,[1][2] but sometimes astronomical summer is defined as starting at the solstice, the time of maximal insolation, often identified with the 21st day of June or December. A variable seasonal lag means that the meteorological centre of the season, which is based on average temperature patterns, occurs several weeks after the time of maximal insolation.[3] The meteorological convention is to define summer as comprising the months of June, July, and August in the northern hemisphere and the months of December, January, and February in the southern hemisphere.[4][5] Under meteorological definitions, all seasons are arbitrarily set to start at the beginning of a calendar month and end at the end of a month.[4] This meteorological definition of summer also aligns with the commonly viewed notion of summer as the season with the longest (and warmest) days of the year, in which daylight predominates. The meteorological reckoning of seasons is used in Australia, Austria, Denmark, Russia and Japan. It is also used by many in the United Kingdom and in Canada. In Ireland, the summer months according to the national meteorological service, Met Éireann, are June, July and August. However, according to the Irish Calendar, summer begins on 1 May and ends on 1 August. School textbooks in Ireland follow the cultural norm of summer commencing on 1 May rather than the meteorological definition of 1 June.

In midsummer, the sun can appear even at midnight in the northern hemisphere. Photo of midnight sun in Inari, Finland.

Days continue to lengthen from equinox to solstice and summer days progressively shorten after the solstice, so meteorological summer encompasses the build-up to the longest day and a diminishing thereafter, with summer having many more hours of daylight than spring. Reckoning by hours of daylight alone, summer solstice marks the midpoint, not the beginning, of the seasons. Midsummer takes place over the shortest night of the year, which is the summer solstice, or on a nearby date that varies with tradition.

Where a seasonal lag of half a season or more is common, reckoning based on astronomical markers is shifted half a season.[6] By this method, in North America, summer is the period from the summer solstice (usually 20 or 21 June in the Northern Hemisphere) to the autumn equinox.[7][8][9]

Reckoning by cultural festivals, the summer season in the United States is traditionally regarded as beginning on Memorial Day weekend (the last Weekend in May) and ending on Labor Day (the first Monday in September), more closely in line with the meteorological definition for the parts of the country that have four-season weather. The similar Canadian tradition starts summer on Victoria Day one week prior (although summer conditions vary widely across Canada's expansive territory) and ends, as in the United States, on Labour Day.

In Chinese astronomy, summer starts on or around 5 May, with the jiéqì (solar term) known as lìxià (立夏), i.e. "establishment of summer", and it ends on or around 6 August.

In southern and southeast Asia, where the monsoon occurs, summer is more generally defined as lasting from March, April, May and June, the warmest time of the year, ending with the onset of the monsoon rains.

Because the temperature lag is shorter in the oceanic temperate southern hemisphere,[10] most countries in this region use the meteorological definition with summer starting on 1 December and ending on the last day of February.[11][12]

Wet season thunderstorm at night in Darwin, Northern Territory, Australia.

Summer is traditionally associated with hot or warm weather. In Mediterranean climates, it is also associated with dry weather, while in other places (particularly in Eastern Asia because of the monsoon) it is associated with rainy weather. The wet season is the main period of vegetation growth within the savanna climate regime.[13] Where the wet season is associated with a seasonal shift in the prevailing winds, it is known as a monsoon.[14]

Image of Hurricane Lester from late August 1992.

In the northern Atlantic Ocean, a distinct tropical cyclone season occurs from 1 June to 30 November.[15] The statistical peak of the Atlantic hurricane season is 10 September. The Northeast Pacific Ocean has a broader period of activity, but in a similar timeframe to the Atlantic.[16] The Northwest Pacific sees tropical cyclones year-round, with a minimum in February and March and a peak in early September. In the North Indian basin, storms are most common from April to December, with peaks in May and November.[15] In the Southern Hemisphere, the tropical cyclone season runs from the start of November until the end of April with peaks in mid-February to early March.[15][17]

Thunderstorm season in the United States and Canada runs in the spring through summer but sometimes can run as late as October or even November in the fall. These storms can produce hail, strong winds and tornadoes, usually during the afternoon and evening.

Hotels and tourists along the Atlantic Ocean shoreline in Myrtle Beach, South Carolina in summer

People generally take advantage of the high temperatures by spending more time outdoors during summer. Activities such as travelling to the beach and picnics occur during the summer months. Sports such as soccer, basketball, football, volleyball, skateboarding, baseball, softball, cricket, tennis and golf are played. Water sports also occur. These include water skiing, wakeboarding, swimming, surfing, tubing and water polo. The modern Olympics have been held during the summer months every four years since 1896. However, the 2000 Summer Olympics, in Sydney, were held during the Spring and the 2016 Summer Olympics, in Rio de Janeiro, were held in Winter.

Summer is normally a low point in television viewing, and television schedules generally reflect this by not scheduling new episodes of their most popular shows between the end of May sweeps and the beginning of the television season in September, instead scheduling low-cost reality television shows and burning off commitments to already-cancelled series. There is an exception to this with children's television. Many television shows made for children and are popular with children are released during the summer months, especially on children's cable channels such as the Disney Channel in the United States, as children are off school. Disney Channel, for example, ends its pre-school programming earlier in the day for older school-age children in the summer months while it reverts to the original scheduling as the new school year begins. Conversely, the music and film industries generally experience higher returns during the summer than other times of the year and market their summer hits accordingly. Summer is most popular for animated movies to be released theatrically in movie theaters.

With most school-age children and college students (except those attending summer school and summer camp) on summer vacation during the summer months, especially in the United States, travel and vacationing traditionally peak during the summer, with the volume of travel in a typical summer weekend rivalled only by Thanksgiving. Teenagers and college students often take summer jobs in industries that cater to recreation. Business activity for the recreation, tourism, restaurant, and retail industries peaks during the summer months as well as the holiday season.

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  Children cycling during summer
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  Barefoot skiing
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  Fig trees bear fruit when summer is near
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  Using a handheld fan in summer

• Summer Olympic Games