New York City was hammered by a hurricane in early September 1821 and the ferocious storm caused flooding, property damage, and loss of life. In an era before scientific weather forecasting, the hurricane took an unprepared city completely by surprise.

The "Great September Gale" lived on in vivid memories of its survivors. Yet it might have been forgotten had it not become a milestone in the new science of meteorology.

As the storm passed through New England it blew down hundreds of trees. A Connecticut resident with scientific inclinations, William C. Redfield, walked along the path of the storm, making careful notes on how the trees fell.

Redfield's observations made him realize the severe winds seemed to rotate. Understanding that concept led to our modern understanding of hurricanes.

The Hurricane of 1821 Hit New York Hard

After two days of rain, a hurricane slammed into New York City on the afternoon of Monday, September 3, 1821. With the city completely unprepared for such a monstrous storm, the damage was enormous.

The East and Hudson Rivers flooded over their banks, causing considerable flooding in lower Manhattan. And the hurricane force winds damaged structures throughout New York City, Brooklyn (which was still a separate city), Long Island, and New Jersey.

The next day’s newspaper, the New York Evening Post of September 4, 1821, published a dramatic account of the storm, headlined "Tremendous Gale."

The story described a storm lasting from 4:30 pm to 8:30 pm, striking with "all the violence and fury of a hurricane… throwing down chimneys, unroofing buildings, and prostrating trees in various directions."

"When the gale was at its height it presented a most awful spectacle," the newspaper reported. "The falling of slate from the roofs of buildings, and broken glass from the windows, made it unsafe for any one to venture into the streets."

The newspaper noted that the city had actually been fortunate, as the storm had arrived during low tide. Still, it mentioned that the tide "rose to an unusual height, overflowing all the wharves and filling the cellars of all the stores on the margin of the East and North [Hudson] Rivers."

The article continued: "Great quantities of lumber, and other property on the wharves, have either floated off or been damaged."

The 1821 Hurricane Became Known as The Great September Gale

The newspaper then listed a number of calamitous events, which included wharves being ripped from their foundations and houses being torn apart in the high winds. There are numerous descriptions of boats, including ferries, steamships, schooners, and brigs, being gravely damaged or sunk.

A house on Broadway blew down and killed ten cows. And in one dramatic incident, "Mrs. Dawning’s house on the Bowery was blown down – the family, in occupying the upper part, made their escape into the yard but a moment before it fell."

The Bloomingdale Road, which today is upper Broadway in Manhattan, was reported to be "almost impassable by the falling of trees."

On the same page of the New York Evening Post, a report from Jersey City, New Jersey noted that seven sailors from a U.S. Navy vessel in the harbor were missing and presumed drowned.

New York City recovered from the storm, and in time the stories about what came to be known as "The Great September Gale" were more or less forgotten. But that storm had an important legacy thanks to dramatic damage caused after it moved beyond New York and devastated parts of New England.

William C. Redfield Studied the Trees Knocked Over In the 1821 Hurricane

A native of Connecticut, William C. Redfield grew up with a strong interest in science, and educated himself by borrowing books on scientific subjects. He was also known to be a prodigious walker, at times taking long treks from New England to visit relatives who had settled in Ohio.

Following the great storm of 1821, Redfield walked through a large area of Connecticut which had been devastated by the high winds. He was intrigued to notice that in some areas the trees had been knocked down with their tops pointing to the northwest. In other areas, trees were arranged in the opposite direction, with their tops pointing to the southeast.

Redfield's Theory of Hurricanes Became Accepted Science

The patterns of the battered trees convinced Redfield that hurricanes were complex circular storms, and he eventually published a paper on the topic in the American Journal of Science in 1832. Redfield's theory was that a hurricane was a great traveling whirlwind.

Today we take that idea for granted, but at the time it was a new way of thinking about hurricanes. Prior to Redfield, the accepted belief was that the winds of hurricanes blew steadily from one direction.

Over time Redfield collected information on other great storms, and what he discovered bolstered his thesis. Redfield also developed a correspondence with a British naval officer who also studied storms, Sir William Reid. The two men continued their research and writing about great storms, and as the science of meteorology developed throughout the 1800s, their writings formed the basis for our understanding of hurricanes.

William C. Redfield was also involved with a diverse variety of projects, including work with early steamboats and locomotives, and he published more than 60 scientific papers before his death in 1857. But his outstanding contribution to science would be his theory of hurricanes, which resulted from his walking the path of the Great September Gale of 1821.