June 5, 1925: Rainfall totals in the northeastern United States from January through the end of May 1925 had only reached half the normal total in most cities. This meant, at least for the first 5 months of the year the climate was more like patched central Texas than the lush and green landscape of the eastern seaboard. Heating of the lower atmosphere takes place when the ground is heated and transfers that heat to the air closet to the ground. When the ground is moist some of the sun’s energy goes into evaporating the moisture rather than heating the ground. When the ground is dry that doesn’t happened the ground heats up quickly. It’s one reason why it’s so much hotter in Texas and New Mexico and Arizona then the East. An unusual warm air mass moved over the eastern part of the nation in the first week of June 1925 and that coupled with the already dry ground lead to extraordinary early summertime heat. On June 5 the mercury reached 100 in Washington DC – the earliest on record in fact that was in the middle on a string of high temperatures in DC that reached 97 or higher for 5 consecutive days.. On June 5 1925 Philadelphia also reach 100 for the earliest ever there as well.
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