According to the Old Farmer’s Almanac, “the Dog Days of Summer are traditionally the 40 days beginning July 3 and ending August 11, which coincide with the dawn rising of Sirius, the Dog Star, the brightest of the stars. This is soon after the Summer Solstice, which of course also indicates that the worst summer heat will soon set in.”
Try lakeside / beach time with your dog (and family?) to “take the edge off” July heat, or, grab a telescope some night and look for Canis Major (Big Dog) with Sirius shining brightly. And take a look at the Astronomy Subject Guide.