Sky blue as a colour concept is as old as human observation of the sky. As a named pigment colour, it emerged in the 18th–19th century alongside the tradition of plein air landscape painting. The Romantic and Impressionist movements made sky painting central to Western art — Constable's cloud studies elevated meteorological observation to high art.

Open, free, and optimistic. Sky blue is perhaps the most universally positive colour across human cultures — the sky is one of the few constants of human experience regardless of geography. Associated with freedom, possibility, and the lightness of being. Psychologically it reliably promotes calm and expansiveness.

Sky blue appears in the national flags of more countries than any other colour — Argentina, Greece, Israel, Finland, and many others use sky blue to represent their national identities. In Christian art, the sky blue of the Virgin's inner garment (distinguished from her ultramarine outer robe) represents her heavenly nature. Baby blue for boys emerged in early 20th century Western culture — a relatively recent colour-gender association.