Just as the 60s were cool in summer, the 30s were hot across the Upper Peninsula and much of the United States. On July 18, 1932, Ironwood??s temperature soared to a daily-record 94 degrees. This is one of 17 daily high temperature records set in July from the 30s. All these records still stand. It??s a remarkable testament to the persistent hot summers of that era. The first graph above shows state high temperature records set across the entire country. The absolute peak is the torrid summer of 1936.
We??ve mentioned this often before, but it bears repeating: the hot summer temperatures of the 30s were, in part, the result of drought conditions that developed over the Plains. When it??s dry, the sun can more effectively heat the air because its energy isn??t wasted in evaporating moisture out of the soil. Of course, you still need the right weather pattern to develop the heat. That ideal pattern for heat occurred many times during the summer of the 30s. Interestingly, it appears that at least one record from the 30s was broken during this heat wave. Iron Mountain hit 94 on Tuesday. That broke the old record of 93 set on July 16, 1931.
Iron Mountain residents suffered through four straight days above 90 degrees, but today was the last in the string. The big upper ridge that built over the weekend over the Lower Great Lakes (Image 2) is finally breaking down. This ridge or upper-air high is essentially a dome of heat. By the weekend, the system is forecast to be replaced by a trough (Image 3). That means temperatures will actually cool to somewhat below average for Saturday and Sunday.