The correct phrase in Spanish is ‘cielo azul’.
In Spanish, adjectives typically follow the nouns they describe. In this case, cielo means sky and azul means blue. Therefore, when you want to say blue sky, you would correctly say ‘cielo azul’.
Using ‘azul cielo’ is not grammatically correct in standard Spanish usage. This structure might confuse listeners because adjectives used before nouns can change the meaning or emphasis. In this scenario, adhering to the common adjective-noun order helps maintain clarity in communication.