Photo of midnight sun in Inari, Finland.ĭays 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. In the middle of summer, the sun can appear even at midnight in the northern hemisphere. By the Irish calendar, summer begins on 1 May ( Beltane) and ends on 31 July ( Lughnasadh). In Ireland, the summer months according to the national meteorological service, Met Éireann, are June, July and August. It is also used by many people in the United Kingdom and Canada. The meteorological reckoning of seasons is used in countries including Australia, New Zealand, Austria, Denmark, Russia and Japan. 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. 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. 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.

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. By solar reckoning, summer instead starts on May Day and the summer solstice is Midsummer. Further information: Meteorological seasonsįrom an astronomical view, the equinoxes and solstices would be the middle of the respective seasons, 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.

When does summer start