dog days (of summer) or canicular days. The hot, sultry period of summer between early July and early September, or even more metaphorically, a period of stagnation or a time in which evil influences prevail.
This phrase even has an original Latin version—dies caniculares or Dog Star days—from which it is translated. The name derives from the fact that the Dog Star (Sirius) rises and sets with the sun during these days. The Romans' belief was that this added light caused the additional heat that is experienced in the northern temperate regions at this time of year.
Did they really think that any star, however bright, could actually raise earthly temperatures? Well, maybe, the solstice comes early in what we think of as summer weather and even as the sun is in the sky less and less each day, the temperature rises.
In the heat, I myself prefer lethargy. Unfortunately there is air conditioning.
canicular. Of or pertaining to the dog-days. Or, humorously, pertaining to a dog.
The ancient Egyptian year, computed from one heliacal rising of Sirius to the next. Not exactly like the year of the dog since it's every year; it's just a matter of determining when you celebrate new year's.
1. The Oxford English Dictionary Online. 2005. 3d ed. Accessed from http://dictionary.oed.com.
About the illustrations: Figure 1 is photography by Patricia Ramirez. Used by permission.
Figure 2 is NASA artist G. Bacon's impression of how the Sirius binary system appears up close, as it were. This file is in the public domain because it was created by NASA and the European Space Agency.
Figure 3 is an image associated with the Year of the Dog in the Chinese calendar. © 2009 Jupiterimages Corporation.