How did weather play a role in the Great Chicago Fire?

One hundred fifty years ago, a barn fire that broke out on the west side of Chicago changed the lives of residents forever. While the cause of the fire is still undetermined, weather was a major factor that led to its powerful 30-hour rampage through the city, and potentially played a role in its eventual demise.

On Oct. 8, 1871, The O'Leary Barn on the west side of Chicago erupted in flames.

"Chicago was a city made almost entirely of wood," Carl Smith told AccuWeather Senior TV Weather Broadcaster Adam Del Rosso on a recent episode of AccuWeather Prime. "It was very, very fire-prone."

Smith, who is a historian and author of Chicago's Great Fire, told Del Rosso that the city had faced a very dry summer before the fire erupted -- a factor that had a significant role in the destruction and loss of life that followed.

In Chicago, weather patterns can change dramatically depending on wind direction. A southwest wind often brings in air from land and can keep temperatures high and the weather dry, while a wind from the northeast often brings air from the Great Lakes into the city, which can have a cooling effect. The winds in Chicago on the day of the fire were coming from the southwest, and the temperature in the city that day was in the 80s F, which is unseasonably warm for early October.

"We don't know for sure how it started," Smith said. "The remarkable thing is how an ordinary small fire could burn down a whole city, and the wind played a large role in that."

(National Fire Protection Association)

The winds then blew the flames from the barn into the city center.

"It was a very bad summer for fires," Smith continued, adding that after fall arrived, "there had been about two dozen fires in the week before the great one, including a big one the night of Oct. 7."

The fire, being so enormous and difficult to get under control, continued burning for about 30 hours, igniting late on Sunday night and continuing on until the early hours of Tuesday.

Compounding matters, there was a failure in the signal system for the fire department, so by the time firefighters were on the scene, the fire was already uncontrollable. The winds in the area made it even more difficult to put out the flames. When firefighters tried to hose the fire down, the water turned into mist from the wind.

"The super-heated air sent big chunks of burning Chicago up into the air and then the wind blew them farther ahead, landing on these wooden buildings throughout the city, starting other fires which then went their own different ways and then recombined," Smith explained.

(National Fire Protection Association)

The fire was so unmanageable, Smith said the firefighters were unable to put it out at all, and it ended up burning itself out. On Tuesday morning, the weather finally began to cooperate as well when rain started to fall.

Some 300 people died, which Smith said was "remarkable" considering the size of the fire and the population of Chicago at the time -- around 300,000. The infrastructure of the city was not as successful at surviving, however. About one-third of the buildings in Chicago, roughly 18,000 structures, were destroyed in the Great Chicago Fire.

Weather continued to be a challenge for Chicago when it came time to rebuild -- winter was approaching and mixing cement and mortar is more difficult to do in cold weather.

"The most remarkable thing in many ways is after the city burnt, is how quickly it was rebuilt," Smith said.

The fire had such a lasting impact on the city of Chicago that one of the four stars on the city's flag represents the fire.

"Chicago was very slow to take meaningful fire prevention steps, it was not a particularly safe city," Smith explained.

(National Fire Protection Association)

Eventually, insurance companies refused to insure for fires in the city until officials took steps toward fire prevention, which pushed Chicago to finally take those needed steps.

"Basically, the history of fire prevention is the reaction to one fire after another," Smith said. "But we see many things, we see better exits, we see wider streets," Smith said. "We see obviously better manufacturing of stoves and heaters."

Smith said the lessons of that terrible tragedy 150 years ago echo in modern life. "Fire prevention is very much a work in progress," he said, "and something we have to keep our eye on all the time."

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