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Call this hot? On this date a century ago, Philly became a ‘furnace’ on record hottest day

On this date 100 years ago, the heat claimed at least nine lives, sickened 'hundreds,' and forced officials to send thousands of war industry workers home.

Aerial view of Hog Island shipyard in 1918. Those were hot times.
Aerial view of Hog Island shipyard in 1918. Those were hot times.Read moreHistorical Society of Pennsylvania

The Gray's Ferry Bridge buckled from the heat. At Hog Island, the site of what was believed to be the world's largest shipyard, 26,000 workers were sent home.

"To step from a house door into the street was to face almost a furnace-breath," the Inquirer wrote on its front page about the historically hot day of Aug. 7, 1918, as World War I was entering its final months and the region was an international industrial powerhouse.

The city was hotter than a high fever. The official high in Philadelphia was 106, an all-time for any date in the period of record, dating to 1872. At least nine deaths were reported, and that was long before the concept of "heat-related mortality."

In addition, "Prostrations ran into the hundreds," the Inquirer reported the next day.

Those were extreme times. The record high followed a winter in which the temperature had fallen below zero four different times (Philly hasn't had a single zero reading since 1994), and a month before the onset of the catastrophic Spanish flu epidemic blamed for 30 million deaths worldwide, more than 12,000 of them in Philadelphia.

According to the Inquirer (so it must have been true) it reached 106.2 at 3:50 p.m. on that white-hot Wednesday in 1918. The paper reported a reading of 122 at Hog Island, about which we would be mightily skeptical.

>>READ MORE: Philly-area heat indexes heading to triple digits as "dog days" gain steam

We're not sure where that Hog Island reading might have been taken, but perhaps coincidentally, based on the official temperature and humidity, we estimate that the heat index would have been close to 122.

It was indisputably hot, the second consecutive day of 100-plus temperatures in a summer that got off to a refreshingly temperate start without a single 90-plus reading until July 16.

The Inquirer said that a saving grace on Aug. 7 was the relative lack of humidity, at 38 percent, a "merciful boon granted to mankind."

Actually, had it been more humid, the temperature in all likelihood would have never made it to 106. More water vapor in the air would have forced the sun to use some of its energy to burn it off, rather than heat the surface.

The record for Aug. 8 is a rather prosaic 100, set in 2001, and the temperature won't even get close Wednesday, with a forecast high of 92. The modest heat wave is due to end by Thursday, when daytime highs fall back into the 80s.