What are the Dog Days of Summer?

Tricia Christensen
Tricia Christensen
Tricia Christensen
Tricia Christensen

The dog days of summer seems a natural expression. In hot weather dogs pant and lie as flat on the ground as they can to avoid the heat. The expression doesn't originate with the behavior of dogs during the summer, however. It reaches farther back in time to some mistaken astronomical impressions of the Greeks and Romans.

Dogs prefer to lie down during hot summer days.
Dogs prefer to lie down during hot summer days.

During hot weather, particularly the period from mid-July through August, the star Sirius, part of the constellation Canis Major, rises and sets with the sun. It was believed by the ancients that this conjoined rising and setting produced extra heat for the Earth. This explanation was used to account for the hot and sultry heat produced during the summer months.

Of course, we now know that, while Sirius produces a tiny amount of light energy in our direction, it isn't responsible for the dog days of summer. The hot weather is actually caused by the tilt of the Earth in relationship to the Sun. In the Northern Hemisphere, this slight tilt allows the Earth to receive more direct sunlight beginning on June 21st. In the Southern Hemisphere, the dog days would actually occur during December, when countries like Australia are tilted slightly more toward the sun and receiving a greater amount of sunlight.

Panting helps dogs deal with heat.
Panting helps dogs deal with heat.

Another mistaken impression about the dog days of summer is that they occur when the Sun is closest to the Earth. This is actually not true, though it is the case that the Earth's distance from the Sun varies slightly during its orbit. Tilt, instead of distance, determines the amount of direct sunlight the Earth gets, and during the Northern Hemisphere in July, the planet is actually farthest from the Sun.

It was once believed that dogs would be more susceptible to contracting rabies during the dog days of the summer.
It was once believed that dogs would be more susceptible to contracting rabies during the dog days of the summer.

The days described as the dog days of summer are often given a specific date, though there has been different opinions on the actual dates. Some describe the date as between 3 July and 11 August, and others suggest 6 July through 17 August. Most agree that the dog days last 40 days.

Beaches become a popular destination during the dog days of summer.
Beaches become a popular destination during the dog days of summer.

The phrase picked up new meaning in the 19th century. It was believed that dogs would most often contract rabies during this time period. A scene in To Kill A Mockingbird suggests this belief continued well into the 20th century, when a mad dog is shot by Atticus Finch. All notice that it isn't the time of year for rabies to occur since the shooting occurs well before the summer months.

Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent wiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent wiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

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Discussion Comments

anon164173

Amen, South Carolina here, 64 years old and I was taught the same thing. My daughters laughed when I mentioned it. Thanks for the comment, glad I'm not the only old fogey. --Diane

christensen

That's a great addition! Thanks for adding that extra information.

anon100378

Hello, just a note about "Dog Days." I grew up in the South, in North Georgia. It was always believed that wounds, sores, etc. would not heal well during Dog Days. Your article does not mention this belief or myth. I just thought I would share.

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    • Dogs prefer to lie down during hot summer days.
      Dogs prefer to lie down during hot summer days.
    • Panting helps dogs deal with heat.
      Panting helps dogs deal with heat.
    • It was once believed that dogs would be more susceptible to contracting rabies during the dog days of the summer.
      It was once believed that dogs would be more susceptible to contracting rabies during the dog days of the summer.
    • Beaches become a popular destination during the dog days of summer.
      Beaches become a popular destination during the dog days of summer.
    • Outdoor picnics are popular during the dog days of summer.
      Outdoor picnics are popular during the dog days of summer.
    • Block parties are a popular activity during the dog days of summer.
      Block parties are a popular activity during the dog days of summer.
    • It is important for people to stay hydrated during the dog days of summer.
      It is important for people to stay hydrated during the dog days of summer.