Dog Days of Summer Origins Explained

We know the “dog days” of summer to represent the hottest days of the year which occur in July through August. We’ve experienced these conditions the past couple weeks with one heat wave and another starting tomorrow. The exact timing of this period was set by the Old Farmer’s Almanac to be from July 3rd to August 11th. Why this particular time period? The answer dates back to ancient Greece.

Ancient Greeks happened to notice that the heat of the late summer coincided with the star Sirius rising in the morning along with our sun, visible just before sunrise. Sirius is very prominent and bright throughout winter and spring but disappears from view as it is behind the sun until coming back into view in July. To no surprise for Harry Potter fans, Sirius was known as the “Dog Star” as it is the brightest star in the sky and its constellation Canis Major (Greater Dog). The Greeks therefore believed that the heat was brought on by Sirius. They also suspected that Sirius brought evils other than heat, including fevers and foreboding of evil things to come.

Other peoples throughout history noticed this as well and the name stuck through uses in popular culture, from the Illiad to A Christmas Carol to popular lyrics. Today it remains known as the hottest days of the year, occurring in the late summer. If you happen to be out before sunrise this week, if you can bear the heat, look up towards the eastern sky to catch a glimpse of Sirius rising along with the sun and hot temperatures of the day. Luckily for us, the “dog days are over” by next week as cooler temperatures return once again.