Sirius signified certain emanations which caused its malignant influence. Anyone suffering its effects was said to be "star-struck" (, "astrobólētos"). It was described as "burning" or "flaming" in literature. The season following the star's reappearance came to be known as the "dog days". The inhabitants of the island of Ceos in the Aegean Sea would offer sacrifices to Sirius and Zeus to bring cooling breezes, and would await the reappearance of the star in summer. If it rose clear, it would portend good fortune; if it was misty or faint then it foretold (or emanated) pestilence. Coins retrieved from the island
Dog days even recorded the belief that the return of the bright star was responsible for bringing heat and fever with it; it was also associated with sudden thunderstorms. In Homer's "Iliad", probably composed in the but representing an earlier tradition, Achilles' approach towards Troy, where he will slay Hector, is illustrated through an extended metaphor about the baleful effects attending the return of Sirius: The rising of Sirius during this period has been calculated as 19 July (Julian). Writing about the same time, Hesiod, however, considered the worst and hottest part of the summer to be the days "before" Sirius returned