In answering the question Is there a term for “midnight” that is like “noon”, I came across the phrase noonday night listed as a synonym for midnight in my copy of Roget's International Thesaurus—attributed to Longfellow. I included the reference in my answer, but after reading the passage more carefully, I'm not so sure it is referring to the middle of the night. Searching this phrase turns up many usages by other authors, but I'm unable to determine from them what exactly is being referred to.
I'm wondering if it could be a description of an eclipse, or some permutation of the midnight sun phenomenon. Can anyone offer some insight? What did this phrase originally mean and when was it first used?