Old Farmer's Almanac

Traditionally, the Dog Days begin on July 3 and last 40 days, ending August 11, coinciding with the heliacal (“at sunrise”) rising of the Dog Star, Sirius. The phrase “Dog Days” conjures up the hottest, most sultry days of summer, although Sirius doesn’t actually affect the weather. Since its rising also coincides with a time of extreme heat, the connection with hot, sultry weather is obvious: “Dog Days bright and clear / indicate a happy year. / But when accompanied by rain, / for better times our hopes are vain.”