Started reading The Rings of Saturn by W. G. Sebald and came across the words, "dog days".

Apparently, the term "dog days" comes from a star.

(thanks wikipedia!)

The dog days or dog days of summer are the hot, sultry days of summer. They were historically the period following the heliacal rising of the star system Sirius (known colloquially as the "Dog Star"), which Hellenistic astrology connected with heat, drought, sudden thunderstorms, lethargy, fever, mad dogs, and bad luck. They are now taken to be the hottest, most uncomfortable part of summer in the Northern Hemisphere.

A few lines later, he does mention the dog star.

certain ailments are more likely to beget us under the sign of the dog star.