July 's the seventh month of the year in the Gregorian Calendar and one of seven Gregorian months with the length of 31 days. It's, on average, the warmest month in most of the Northern hemisphere (where it's the second month of summer) and the coldest month in much of the Southern hemisphere. The second half of the year commences in July. The birthstone for July's a red ruby. In the Northern hemisphere: Dog days begin in early July, when the hot sultry weather of summer usually starts. Summe… (More on July)