It can get mighty hot in July, even here in the mountains of Central Pennsylvania. This most recent hot spell pales in comparison, though, to a couple blistering hot summers eight decades ago. Eighty years ago on July 9 and 10, 1936 the thermometer hit 98 and 99 degrees, the peak of a heat wave that lasted nearly three weeks in the Northeast United States. During that spell we went two full weeks without a drop of rain. The highest temperature every recorded in Pennsylvania, 111 degrees, was reached in Phoenixville, just north of Philadelphia, on those same days.
Altoona's 98 and 99 degree readings on those two dates was the second hottest two day spell on record. August 3 and 4, 1930 were 100 and 102, August 4th being the second hottest day ever in Altoona. (For you trivia hounds, the hottest temperature recorded was 103 on July 22, 2011.) Only a dozen days have ever gotten to 99 or higher in Altoona and seven were during the Thirties. The most extreme heat nationwide occurred two Julys before the '36 hot spell on July 21, 1934 when 43 states recorded temperatures over 90 degrees. (That was the first time that had happened since widespread temperature statistics had begun being recorded.) When it hit 103 in Carlisle that day many likely thought it couldn't get any hotter. Four days later it reached 104, yet that wasn't the hottest place in the state. Tamaqua took the prize at 108 that afternoon.
That was during one of the worst hot and dry spells of the Dust Bowl and the heat and drought spread across a large portion of the country. The disaster and its accompanying dust storms were at their worst in Texas and Oklahoma. While not so horrid as the Southern Plains, the heat and lack of rain cursed a much larger area, ultimately bankrupting farmers from one end of the country to the other. "Extreme" and "Severe" drought covered an area from Central Texas north to the Southern Plains of Canada, west to Central Washington and Oregon and east to the Western New York in July 1934. Our own Juniata River watershed was included in the severe drought area.
Already in the economic nightmare of the Great Depression, the catastrophic drought, heat and resulting windstorms produced perhaps the worst environmental disaster in the nation's history. Such large scale dryness perpetuates and magnifies the existing heat and drought conditions. Higher temperatures increase water evaporation from soils and places that are already relatively dry are pushed over the edge. Seeds sometimes never even sprout and native grasses struggle to hang on. Despite great improvements in soil conservation efforts, some climate scientists fear that global warming could set these same developments into motion here in the 2010s.
Drought puts greater pressure on groundwater extractions for irrigation, even in places like Pennsylvania. Concerns over the long-term depletion of the massive Ogallala Aquifer underneath much of the Great Plains remains a source of anxiety for farmers and geologists in that part of the country. Yet groundwater pressures exist even here in the Keystone State during particularly dry summers like this one, especially as growing populations and suburban sprawl gobble up an ever-increasing portion of those water resources.
Learn more about that decade in two award winning books:
The Worst Hard Time by Timothy Egan and The Dust Bowl by Donald Worster.
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The Flood of 1947
The Hottest Day
Rising Sea Level
Cold Winters & Big Pictures
Rainy Junes: 1972 & 2015
Penn State's Weather World
The Paris Accord
2016's Peculiar Snowstorm
Two Different Winters: 1936 & 2016
The Year Without A Summer
Pennsylvania's Hottest Summer