Expand: date=July 2008

Summer is one of the four temperate seasons, marked by the warmest time of year with the longest days.

A field in summer

Period

The seasons are popularly considered to start on different dates in different cultures. In some Western countries, especially the USA, they are believed to start at the equinoxes and solstices, based on a misunderstanding of astronomical reckoning. Thus, in the Southern Hemisphere, based on this premise summer begins on the day of the December solstice and ends on the March equinox. When it is summer in the southern hemisphere it is winter in the northern hemisphere, and vice versa. From a purely astronomical viewpoint, the equinoxes and solstices would be the middle of the respective seasons, but a variable seasonal lag means that the meteorological start of the season, which is based on average temperature patterns, occurs several weeks later than the start of the astronomical season. According to meteorologists, summer extends for the whole months of December, January and February in the southern hemisphere, and the whole months of June, July and August in the northern hemisphere. 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. From the astronomical perspective, days continue to lengthen from equinox to solstice and summer days begin to 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.

Today, the meteorological reckoning of the seasons is used in Australia, Denmark and the former USSR; it is also used by many people in the United Kingdom, where summer is thought of as extending from mid-May to mid-August. The definition based on equinoxes and solstices is more frequently used in the United States where many regions have a continental climate with a temperature lag of about half a season.

Elsewhere, however, the solstices and the equinoxes are taken to mark the mid-points, not the beginnings, of the seasons. In Chinese astronomy, for example, summer starts on or around May 5, with the jiéqì (solar term) known as Lixia (立夏), i.e. "establishment of summer", and it ends on or around August 6. An example of Western usage would be William Shakespeare's A Midsummer Night's Dream, where the play takes place over the shortest night of the year, which is the summer solstice.

In Ireland, summer begins on 1 May and ends 31 July, due to the Irish calendar.

In southern and southeast Asia, where the monsoon occurs, summer is more generally defined as lasting from March to May/early June, their warmest time of the year, ending with the onset of the monsoon rains.Fact: date=May 2008

From a popular culture point of view, in some areas of the United States, summer season is often considered to begin at the Memorial Day weekend (the last Monday in May) and end at the Labor Day weekend (the first Monday in September). Likewise, another set of pop-cultural reference points for summer is the time when elementary and secondary schools close down for the "summer vacation". This period usually lasts from around early to mid June until around late August to early September, depending on where the school is located.