
1) June 21 or 22
Found on
https://www.crosswordclues.com/clue/summer-solstice

The summer solstice occurs when the tilt of a planet`s semi-axis, in either the northern or the southern hemisphere, is most inclined toward the star (sun) that it orbits. Earth`s maximum axial tilt toward the sun is 23° 26`. This happens twice each year, at which times the sun reaches its highest position in the sky as seen from the north or ......
Found on
http://en.wikipedia.org/wiki/Summer_solstice

(from the article `solstice`) either of the two moments in the year when the Sun`s apparent path is farthest north or south from the Earth`s Equator. In the Northern Hemisphere ... ...event in her honour was the Lgo feast, a midsummer festival celebrated on June 23 (now St. John`s Eve). On that day, the sun, wreathed in a ... ...and ...
Found on
http://www.britannica.com/eb/a-z/s/185

One of the Wiccan eight holy days also known as Litha; celebrated on June 21st of each year.
Found on
http://www.encyclo.co.uk/visitor-contributions.php

The summer solstice denotes the first day of the summer season. For the Northern Hemisphere, the date of summer solstice is either on June 21 or 22 (changes yearly). December 21 or 22 is the date of the summer solstice for the Southern Hemisphere. During the summer solstice, locations in their respective hemispheres experience the longest da...
Found on
http://www.physicalgeography.net/physgeoglos/s.html

[
n] - June 21, when the sun is at its northernmost point
Found on
http://www.webdictionary.co.uk/definition.php?query=summer%20solstice
June 21 noun June 21, when the sun is at its northernmost point
Found on
https://www.encyclo.co.uk/local/20974

The date on which the sun reaches the greatest distance north (in the Northern Hemisphere) or south (in the Southern Hemisphere) of the celestial equator. In the Northern Hemisphere, the summer solstice occurs when the sun in overhead at the Tropic of Cancer (latitude 23° 27' N) about June 21. In the Southern Hemisphere, the summer solstice occurs...
Found on
https://www.encyclo.co.uk/local/21131

the solstice on or about June 21st that marks the beginning of summer in the Northern Hemisphere.
Found on
https://www.infoplease.com/dictionary/summer-solstice
No exact match found.