dog days

The time of year in which it is usually hottest. Although there are no fixed dates on the calendar marking its start and end, the dog days are usually identified with the period running from July 15 to August 15 ("From one Virgin's day to the next, the sun bears down hard"). The word has its etymological origin in the Latin word canis, meaning "dog." The rising of the star Sirius on the horizon marked the beginning of the flooding of the Nile in Ancient Egypt, which coincided with the arrival of summer. Sirius is the brightest star in the constellation Canis Maior (The Greater Dog), hence the curious name given to the hottest period of the year.