sentences:  Of any populated place in the contiguous United States, Yuma is the driest, the sunniest, and the least humid, has the lowest frequency of precipitation, and has the highest number of days per year—175—with a daily maximum temperature of or higher.Yuma features a hot desert climate (Köppen climate classification "BWh"), with extremely hot summers and warm winters.Atmospheric humidity is usually very low except during what are called "Gulf surges", when a maritime tropical air mass from the Gulf of California is drawn northward, usually in connection with the summer monsoon or the passage of a tropical storm to the south.