<P> Spring is a time of major transition in North Dakota . Early spring commonly sees snowstorms, but by late spring as temperatures begin to moderate the state can experience tornado outbreaks, a risk which diminishes but does not cease through the summer and into the fall as North Dakota lies at the northern edge of Tornado Alley . Springtime flooding is a relatively common event in the Red River Valley, due to the river flowing north into Canada . The spring melt and the eventual runoff typically begins earlier in the southern part of the valley than in the northern part . The most destructive flooding in eastern North Dakota occurred in 1997, which caused extensive damage to Grand Forks . </P> <P> Summer sees heat and humidity predominate in the east, while hotter and less humid conditions are generally present in the west . These humid conditions help kick off thunderstorm activity 22--34 days a year . Summer high temperatures in North Dakota average in the mid 80s (30 ° C) in the west to the upper 70s (25 ° C) in the east, with temperatures as hot as 121 ° F (49 ° C) possible . The growing season in North Dakota usually begins in April, and harvest begins in September and October . Tornadoes are possible in North Dakota from April through October, but the peak tornado month is July, followed by June and August . The state averages 13 tornadoes per year . Depending on location, average annual precipitation ranges from 14 in (35.6 cm) to 22 in (55.9 cm). </P> <P> Autumn weather in North Dakota is largely the reverse of spring weather . The jet stream, which tends to weaken in summer, begins to re-strengthen, leading to a quicker changing of weather patterns and an increased variability of temperatures . By late October and November these storm systems become strong enough to form major winter storms . Fall and spring are the windiest times of the year in North Dakota . </P> <P> As of September 2017, the United States Drought Monitor recorded abnormally dryweather conditions across the entire state . The drought is considered severe and unprecedented, and because of its nature as a "unpredictable, sudden event brought on by sustained high temperatures and little rain", it is considered a "flash drought". North Dakota Agriculture Commissioner Doug Goehring announced that predicted economic losses as a consequence from the drought could amount to as much as $4 billion or $5 billion . </P>

When does it start to get cold in north dakota
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