Over the decade of the 1930s, severe drought prevailed across Minnesota during the month of June in 1931, 1933, 1934, 1936 and 1937.

Those years are also noteworthy for heat waves, widespread crop failures, livestock feed shortages and severe windstorms. But June 1933 presented a special challenge to farmers in producing both drought and dual heat waves of equal duration and intensity. There are still many daily high temperature records across Minnesota that remain unbroken from that month of excessive heat.

The first six-day heat wave began June 15, with four counties reporting afternoon temperatures of 100 degrees F or greater. Each day brought more widespread hot temperatures to the state, peaking on June 19 with temperatures of 100 degrees or greater affecting 23 counties.

Daily maximum temperatures in portions of western and southern Minnesota ranged from 101 to 109 degrees. Many overnight low temperatures remained in the 70s, and the reading of 81 degrees the morning of June 19 at Morris still remains the highest minimum temperature for that date in Minnesota history.

The last day of the heat wave, June 20, brought cloudy skies and a few thunderstorms, with welcome rainfall amounts of a quarter-inch to half an inch. These storms were followed by a cool front, which brought a few days of temperatures in the 80s and low 90s.

Heat, round 2

The second six-day heat wave began June 25 in just three western Minnesota counties, where the afternoon temperatures topped 100 degrees. The hot weather spread across the state during the last week of the month, bringing temperatures over 100 degrees to 18 counties in western and southern Minnesota. Daily temperatures rose to as high as 109 degrees.

Again, many overnight low temperatures remained in the 70s during this spell, which lasted until June 30 when thunderstorms again brought welcome rains of 0.25 to 0.75 inches to some areas of the state.

Overall, 41 Minnesota climate stations reported temperatures of 100 degrees or greater during the two heat waves. By the end of the month, the average June temperature across the state was the warmest in history, and it remains so to this day. June 1933 was fully 4 degrees warmer than June 2020 — which most farmers will remember as very hot indeed.

Rainfall in June 1933 was sparse, falling on only five or six days. Twenty-nine Minnesota counties reported less than 1.5 inches of rainfall that month; and by the end of the month, drought had worsened across the state.

According to historical records from the National Climate Data Center, portions of 28 Minnesota counties were listed in severe to extreme drought by the end of June 1933. This drought area expanded to 56 Minnesota counties by August 1933, and many state and federal programs were initiated to bring some financial relief to Minnesota farmers.

June 1933 remains as an anomaly in the state climate record as the only month to ever bring two six-day heat waves of equal intensity and duration.

Seeley is professor emeritus of climatology at the University of Minnesota.