What’s the meaning?
The hottest days of summer, usually at the end of July & beginning of August.
What’s the origin?
The ancient Romans, Greeks or Egyptians noticed that the hottest days of the year, in late July and early August, coincided with the appearance of Sirius – the Dog Star, in the same part of the sky as the Sun. Sirius is the largest and brightest star in the Canis Major constellation, in fact it is the brightest star in the sky. They believed that the star contributed to the heat of the day (because of the Earth’s proximity to the star).