July

"Dog Days"  are the hottest, most sultry days of summer. In the Northern Hemisphere, the dog days of summer are most commonly experienced in the months of July and August, which typically observe the warmest summer temperatures. In the Southern Hemisphere , they occur in January and February, in the midst of the austral summer. The term "dog days" refer to the dog star, Sirius, and its position in the sky. To the ancient Greeks and Romans, the "dog days" occurred around the day when Sirius appeared to rise just before the sun, in late July. They referred to these days as the hottest time of the year, a period that could bring fever, or even catastrophe.

This stretch of hot weather owes itself to the tilt of the Earth's axis, and not any extra help on the part of Sirius. During summer in the Northern Hemisphere, the tilt of the Earth causes the sun’s rays to hit at a more direct angle, and for a longer period of time throughout the day. This means longer, hotter days. The Earth is not actually closer to the sun during this time. But this particular tilt is what helps cause those lazy, hazy days of late summer.

Source: www.news.nationalgeographic.com/2015/07/150710-dog-days-summer-sirius-star-astronomy-weather-language/