The ancient Greek myth of Halcyon is a tender story of love and commitment, which explains the Halcyon sunny days of calm seas and winds. The Halcyon days or Alkionides Meres, as Greeks call them, appear in mid January every year.
Halcyon is a type of kingfisher bird that nests by the sea where sea-charming winds blow, so that its eggs are protected during the nesting period. The phrase Halcyon days today also signifies prosperity, joy, liberation and, of course, tranquility.
Halcyon is a name for a bird of Greek legend which is commonly associated with the kingfisher. The phrase comes from the ancient belief that fourteen days of calm weather were to be expected around the winter solstice - usually 21st or 22nd of December in the Northern Hemisphere. as that was when the halcyon calmed the surface of the sea in order to brood her eggs on a floating nest. The Halcyon days are generally regarded as beginning on the 14th or 15th of December.
Halcyon means calm and tranquil, or 'happy or carefree'. It is rarely used now apart from in the expression halcyon days. The name of the legendary bird was actually alcyon, the 'h' was added in regard to the supposed association with the sea ('hals' in Greek).