midnight sun
From Longman Dictionary of Contemporary Englishmidnight sunˌmidnight ˈsun noun → the midnight sunExamples from the Corpusmidnight sun• It was the first time that I had experienced the midnight sun.• The best time to visit is in June, the time of the midnight sun.• Camping high, between the huts, we enjoyed insect-freeing breezes and spectacular night views of the midnight sun.