Freezing temperatures in May seem counterproductive. Nevertheless, they are a staple of spring weather across the Northern Plains and Upper Midwest. So we cover our flowers and vegetable plants with sheets and blankets and wait for warmer weather. Comparing major National Weather Service reporting stations reveals a wide variety in the frequency of freezing nights in May across the region.
Using the 1991-2020 period of record, the weather stations for Minneapolis, Rochester and Sioux Falls average one freezing morning in May per year. Fargo averages three. Grand Forks, Bismarck and Duluth average four. Dickinson averages seven. International Falls averages nine freezing mornings in the month of May. At all stations, the frequency is higher in early May and tends to drop off later in the month.