 Due to its location in the Great Plains and its distance from both mountains and oceans , the city has a humid continental climate ( Köppen ( Dfb ) ) , USDA Plant Hardiness Zone 4a . This type of climate is distinguished by four very distinct seasons and great variation in temperatures over very short periods of time . As there are no nearby mountain ranges or bodies of water to ameliorate the climatic conditions , Grand Forks lies exposed to numerous weather systems including bitterly cold Arctic high pressure systems . The city experiences long , cold , and snowy winters . In sharp contrast , summers are often warm to hot and often quite humid with frequent thunderstorms . Although warm weather normally ends soon after Labor Day , a few warm days can , on rare occasions , be seen as late as October . Spring and autumn are short and highly variable seasons . Record temperature extremes range from − 43 ° F ( − 42 ° C ) on January 11 , 1912 to 109 ° F ( 43 ° C ) on July 12 , 1936 . The daily mean temperatures of the Grand Forks winters are associated with subarctic climates with frequent subzero temperatures , but due to the extended warm period of daily means above 50 ° F ( 10 ° C ) from May to September it stays within the humid continental temperature range . 
