Ah, the “Dog Days of Summer!” One would think the phase would have to do with dogs or the summer days are “not fit for a dog,” right? Well, not exactly. Here is how “Dog Days” came about. You have to go back to ancient Roman times!
The phrase is actually a reference to Sirius, the Dog Star, which is the brightest star visible from any part of Earth! Sirius is a part of the constellation Canis Major, the Greater Dog.
According to Farmer’s Almanac, during the summer, Sirus rises and sets with the sun — however, on July 23rd, it is in conjunction with the Sun. Because the star is so bright, the ancient Romans believed it actually gave off heat and added to the Sun’s warmth, accounting for the stretch of sultry weather, which is how the phrase “dog days” came about.
“Dog Days of Summer” is typically 20 days before and 20 days after the alignment of Sirus with the Sun, which occurs from July 3 to August 11 each year. The tilt of the Earth causes the Sun’s rays to hit at a more direct angle, and for a longer period of time throughout the day. This leads to longer and hotter days.
Source: “Why are they called the dog days of summer”
Farmers Almanac, July 2022