On July 1, 1776, Thomas Jefferson began recording the weather

Thomas Jefferson purchased a thermometer and barometer and began keeping weather observations 3 days before the Declaration of Independence was signed in 1776.

Three days before the Declaration of Independence was signed on July 4, 1776, Thomas Jefferson purchased a thermometer from a local Philadelphia merchant while he was in town for the signing. He also bought a barometer, one of only a handful for sale in America at the time.

Jefferson immediately began recording weather observations and continued, with a few gaps, until a few days before his death in 1826. Jefferson began with an observation in the morning to capture the low temperature and one in the afternoon to record the high temperature, according to Princeton University.

He soon added barometric pressure, humidity, wind direction and observations of frost, rain, aurora and snow to his organized columnar paper. When he left his home, he recorded observations wherever he traveled, from Washington, D.C., to his retreat in Bedford County, Virginia, and even overseas in France. Jefferson’s collection of weather and climate information is an important historical source for his period, Princeton noted.

Jefferson's enthusiasm for observing the weather was never-ending. He even had a wind vane on the roof of his Monticello home that was connected to a compass rose on the ceiling, allowing him to determine the wind direction without stepping outside.

Recognizing that more people recording more weather observations would be scientifically advantageous, Jefferson tried to get his friend James Madison to join him in 1784. Madison reported that the British had absconded with his weather instruments when they swept through years earlier. He eventually obtained a new thermometer and began taking daily weather measurements.

Jefferson was arguably the most famous weather observer of his era, but he wasn't the first.

Carrying forward amateur scientific investigations that started in the late 1600s as part of the Enlightenment, Dr. John Lining began making weather observations 36 years earlier, in 1738, in Charleston, South Carolina. According to the WMO (World Meteorological Organization), that station maintains the second-oldest continuous weather record in the world.

Although weather instruments had existed for more than 100 years, the telegraph in the mid-1800s enabled the collection of weather data at a central location, the U.S. Signal Office.

On Jan. 1, 1871, the first U.S. weather map was drawn by the "War Department" of the Signal Office. It contained weather reports for about 30 stations, but only a couple of stations west of Omaha, Nebraska, as much of the West lacked weather instrumentation.

The Signal Office would later birth the Weather Bureau, which became the modern National Weather Service.

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