We are moving into the hottest part of the summer, also known as the “dog days.” Generally, the “dog days” start mid-July and last for four to six weeks. Although the phrase is sometimes attributed to the season because dogs would more reliably show signs of madness, it actually goes back to ancient Greece and Rome. The rising of Sirius, or the Dog Star, was considered a sign, and a cause, of the hot, sultry summer weather. Wilting vegetation and flagging energy levels led to the belief that Sirius had a baneful effect on all human activities. Although modern air conditioning and irrigation has changed that somewhat, the description is still used for the season.
Mary Knapp, Weather Data Library