Whenever I hear the phrase “Dog Days of Summer,” I always think about one of our Bretons stretched out on the couch in the air conditioning, hiding from the heat, humidity, and flies that show up in July. But the phrase actually dates back to ancient Greek and Roman times. It comes from the Latin Dies caniculares (dog * days), referring to the period when Sirius, the brightest star in the sky (in the constellation Canis Major), rises just before the Sun in the east after a period of invisibility.
The “Dog Days of Summer” refer to the hot, sultry period in midsummer, historically linked to the Dog Star rather than actual dogs lounging in the heat. Ancient observers noticed Sirius rising with the Sun in July. They believed the combined heat from the Sun and Sirius caused extreme summer heat, droughts, lethargy, mad dogs, thunderstorms, and bad luck.
“Warm summer sun,
Shine kindly here,
Warm southern wind,
Blow softly here.”
~Mark Twain
Traditionally, the period spanned about 40 days: roughly 20 days before and after Sirius’s conjunction with the Sun, around July 23. The association was astrological and observational; folks linked Sirius’s return to the hottest, most uncomfortable weather. But, Sirius has no actual effect on Earth’s weather or temperature; it’s eight and a half light-years away.
The “Dog Days of Summer” is mostly a colorful idiom for the hottest, laziest part of summer; when people (and dogs) seek shade, air conditioning, or take a vacation to the mountains, the lake, or the beach. “Dog Days of Summer” is a beautiful example of how ancient cultures wove the cosmos into explanations for natural phenomena.
The cicada’s dry monotony breaks
over me.
The days are bright
and free,
bright and free.
~Jane Kenyon
The real reasons for the dog days of summer are the Earth’s axial tilt and atmospheric patterns. Long days and direct sunlight cause the ground, oceans, and atmosphere to continue absorbing and retaining heat into July and August, creating a thermal lag. The hottest temperatures arrive weeks after the Summer Solstice. In many regions, high-pressure systems, humidity, and reduced rainfall also contribute to sultry conditions.
We prefer the mountains during the “Dog Days of Summer.” We like to escape to the beach during the “Dead of Winter,” but that’s a story for another blog. A couple of hours from here, along with a mile or so of elevation change, and the temperatures are 30% cooler. The cold mountain streams and giant fir trees get the dogs excited, too.
