Tomorrow we celebrate the anniversary of the signing of the Declaration of Independence. You'd think that the weather in Philadelphia on that historic day in 1776 would have been pretty uncomfortable, given the time of year. But the available weather records suggest otherwise.

The observations of two individuals help us reconstruct the weather of July 4, 1776. Thomas Jefferson was such a diligent weather observer that he took a thermometer with him while away from home. On July 4, 1776, he observed temperatures of 68^oF at 6 a.m., 72^oF at 9 a.m., and 76^oF at 1 p.m. in Philadelphia. We also have more detailed observations from a Mr. Phineas Pemberton, a member of a prominent Philadelphia family. His temperatures for that day are similar to Jeffersonís: 71^oF at 7 a.m. and 76^oF at 3 p.m. In his weather journal, Pemberton also recorded winds shifting from the north to the southwest that day, with decreasing air pressure, and skies becoming cloudy by late afternoon.

So based on the available information, it sounds to me like the weather on July 4, 1776, didn't add any additional stress to the already-momentous events of that historic day.