<P> High desert regions typically have the greatest diurnal - temperature variations, while low - lying humid areas typically have the least . This explains why an area like the Snake River Plain can have high temperatures of 38 ° C (100 ° F) during a summer day, and then have lows of 5--10 ° C (41--50 ° F). At the same time, Washington D.C., which is much more humid, has temperature variations of only 8 ° C (14 ° F); urban Hong Kong has a diurnal temperature range of little more than 4 ° C (7.2 ° F). </P> <P> While the National Park Service claimed that the world record is a variation of 102 ° F (56.7 ° C) (from 46 ° F or 7.8 ° C to − 56 ° F or − 48.9 ° C) in Browning, Montana in 1916, the Montana Department of Environmental Quality claimed that Loma, Montana also had a variation of 102 ° F (56.7 ° C) (from − 54 ° F or − 47.8 ° C to 48 ° F or 8.9 ° C) in 1972 . </P> <P> Diurnal temperature variation is of particular importance in viticulture . Wine regions situated in areas of high altitude experience the most dramatic swing in temperature variation during the course of a day . In grapes, this variation has the effect of producing high acid and high sugar content as the grapes' exposure to sunlight increases the ripening qualities while the sudden drop in temperature at night preserves the balance of natural acids in the grape . </P>

What is the definition of average daily temperature