On July 5, 1911, the mercury in Nashua, New Hampshire peaks at 106 degrees Fahrenheit, one of many record temperatures that are set in the northeastern United States as a deadly, 11-day heat wave hits the area. It would go on to kill at least 380 people—and by some estimates, as many as 2,000.
The heat wave first descended on July 2, and the area from Pennsylvania northeast to Maine was most affected by the stifling heat. New York City was particularly hard hit. In fact, the New York City Health Department put out one of its very first heat advisories during July 1911. Mayor William Gaynor tried to make sure that the city’s ice dealers could keep up their deliveries; in the time before refrigeration, ice was critical in keeping the food supply from spoiling.
By July 13, New York had reported 211 people dead from the excessive heat. One man, apparently disoriented from heat exhaustion, overdosed on strychnine. In Philadelphia, 159 people died from the heat. The types of deaths ascribed to the heat could vary quite a bit in 1911, with some authorities including in the count those who drowned while attempting to cool off by swimming. Most came from heat stroke, when the body's temperature-regulation mechanisms fail, causing body heat to rise to dangerous levels. Heat also sometimes bent rail lines, causing train derailments; deaths in any resulting accidents might also be attributed to the heat.
The end of the 1911 heat wave was marked by a severe thunderstorm that killed five people.