Can you imagine 100 degrees on a day in April? Thirty-six years ago on April 21, it was 100 degrees in Fargo Moorhead. In the middle of a warm and dry spring, an extremely hot, westerly wind developed, under a large upper level high pressure system. The combination of subsidence (downward moving air from aloft) and Chinook (down slope moving air along near the ground) resulted in extraordinary heat across the entire Northern Plains region.
Temperatures in the 90s were widespread. Fargo Moorhead, Grand Forks, along with Waterloo, Iowa, all tied for the national high temperature that day at 100 degrees. This remains the only 100 degree day on record in April in the Red River Valley region.
The weather conditions that day were unique and rare. But when the soil is dry in April (before crops cover the black fields) the air ground can get quite hot which warms the air nicely on sunny days.
Meteorologist John Wheeler