Due to its location in the Great Plains and its distance from both mountains and oceans, Grand Forks has a humid continental climate , USDA Plant Hardiness Zone 4a. It has four very distinct seasons and great variation in temperatures over very short periods of time. As no nearby mountain ranges or bodies of water ameliorate the climatic conditions, Grand Forks lies exposed to numerous weather systems, including bitterly cold Arctic high pressure systems. The city has long, cold, and snowy winters. 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 sometimes occur 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. Due to the extended warm period of daily means above 50 °F (10 °C) from May to September, the city’s climate is still classified within the humid continental temperature range.