Crossword puzzle clue "mid seasons occurrence"

Mid-seasons occurrence?

Rare occurrence at the U.S. Open on Father's Day that's a common occurrence at the U.S. Open on Labor Day

Mid-September occurrence in the night sky

Mid-century filling option in the mid-Atlantic

It usually ranges from the mid-sixties to the mid-seventies

Je ne sais quoi capturing mid-14th to mid-17th century China?

Unlucky occurrence

Unusual occurrence