Crossword clue: the season of the year in which the sun shines most directly upon any region; the warmest period of the year.
1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).
Possible answers
the warmest season of the year; in the northern hemisphere it extends from the summer solstice to the autumnal equinox