I’d heard of Dog Days all my life, but only knew that it referred to the sweltering heat of late summer when dogs laid around more and were more prone to go mad (with rabies). I had a request from a reader to write on the subject in more depth, so if you’re curious as well, read on.

According to Webster, Dog Days are defined as the period between July and early September when the hot, sultry weather of summer usually occurs. The name comes from the ancient belief that Sirius, also known as the Dog Star, was responsible for hot weather. Sirius got the name Dog Star because it is the brightest star in the constellation Canis Major (large dog). Sirius is in fact the brightest star in the heavens. It was so impressively bright that it was thought to produce heat that could reach the Earth, and when Sirius and the Sun appeared close together (astronomers call this “in conjunction”) that the star added to the heat given by the Sun, and so the weather became hotter. Sirius and the Sun appear in conjunction in late July, and so Dog Days became defined as the period of time 20 days before and 20 days after this astronomical event. And according to a Farmer’s Almanac, this time period runs from July 3 to August 11.

The Romans didn’t like hot weather any more than we do, and since Dog Days are normally a time of less rainfall, they worried about their crops. So to appease the wrath of Sirius they would sacrifice a brown dog. Why brown I have no idea. This feeling of apprehension about Dog Days has led to some interesting folklore about them. In the 19th century it was considered an evil time when “seas boiled, wine turned sour, dogs grew mad…causing to man fevers, hysterics, and frenzies”. I’m sure tempers are more apt to run short during hot, miserable weather. As for dogs going rabid, they do, but not any more than other summer months.

Another folk tale is that snakes are more aggressive and will go out of their way to bite you. Dog Days roughly correspond to some snake’s mating season, so while you may see more of them, they are not any more aggressive, but being cold blooded they may be able to move more quickly a larger portion of the day. Another myth is that snakes go blind during the Dog Days of August. Nope. Their vision is temporarily impaired when they shed their skin, but they don’t shed any more in August than the other summer months.

There’s an old English proverb for this goes: “As the Dog Days commence, so they end,”
meaning if they start out either dry or wet, it will be that way the entire 40 days.

By Steve Roark
Volunteer Interpreter, Cumberland Gap National Historical Park