From Longman Dictionary of Contemporary Englishcloudlesscloud‧less /ˈklaʊdləs/ adjective BRIGHTa cloudless sky is clear and has no clouds in it
Examples from the Corpus
cloudless• The sky was inky with cloudless black velvet studded by a million diamonds.• The Moon in a cloudless blue sky is visible directly above the spacecraft.• Think About the temperature in Phoenix, Ariz., on a cloudless day in August.• The night was cloudless, gorgeous.• It was a beautiful cloudless morning and the canopies of the plane trees were lush and transparently golden with sunlight.• And here at the equator, we noted, it was 85 degrees, with cloudless sky and tropical breezes.• Skylarks wheeled and sang high in the cloudless sky.• But the Sun does not shine all the time: even in perfectly cloudless weather, the Sun still sets at night. 