"Dog Days" are the hottest, most sultry days of summer. In the northern hemisphere, they usually fall between early July and early September. In the southern hemisphere they are usually between January and early March. The actual dates vary greatly from region to region, depending on latitude and climate. Dog Days can also define a time period or event that is very hot or stagnant, or marked by dull lack of progress. The name comes from the ancient belief that Sirius, also called the Dog Star, in close proximity to the sun was responsible for the hot weather.