Idiom meaning, usage examples, facts

1. Summer in the southern United States is uncomfortably hot and humid. In July and August, we suffer through the dog days.
2. I can’t stand the dog days of summer. Next year I’m going to buy an air conditioner!

The expression has an astronomical source. It is the time in July and August when, in the northern hemisphere, the Dog Star, Sirius, rises in conjunction with the sun. In ancient times it was believed that it was the combined heat of Sirius and the sun that caused the hot weather.