As the main author of the Declaration of Independence and the third President of the United States, Thomas Jefferson is regarded as one of this country’s Founding Fathers. He was also an astute and systematic weather observer.

Portrait of Thomas Jefferson by Rembrandt Peale, 1805. Credit: NYHS

In the summer of 1776, Jefferson was in Philadelphia, PA to sign the Declaration of Independence.  While there, he purchased a thermometer and a barometer – new and expensive weather equipment at that time. For the next 50 years, he kept a meticulous weather journal.  He recorded daily temperature data wherever he was – at home in Virginia or while traveling.

On July 4, 1776, Jefferson noted that the weather conditions in Philadelphia were cloudy with a high temperature of 76°F.

In an effort to understand the bigger picture of climate in America, Jefferson established a small network of fellow observers around Virginia as well as contacts in a few other states. According to records at Monticello, his estate in Virginia, he hoped to establish a national network for weather observations. While this plan did not come to fruition during his lifetime, today’s National Weather Service considers him the “father of weather observers.”

Happy Independence Day!

An excerpt from Thomas Jefferson’s Weather Journal, July 1776. Credit: NCDC