ELMWOOD PARK, Ill. (CBS) — Much of the Chicago area was under the National Weather Service’s red flag warning Tuesday, meaning “critical fire weather conditions are either occurring now or will occur shortly.”

In the CBS Chicago broadcast area, the red flag warning was in effect for Cook, DuPage, Will, Kendall, Grundy, LaSalle and Kankakee counties in Illinois and Lake, Porter, Newton and Jasper counties in Indiana. Large parts of Illinois as far south as Macomb, Peoria, Bloomington, Champaign and Danville were also affected – as were large parts of northern Indiana and eastern Iowa.

Parks with lots of leaves on the ground — and there are a lot of them in the fall — are the areas where first responders and weather experts say they can pose a problem during red flag warnings. There is a significant risk of these leaves, dry brush or grass catching fire.

The Elmwood Park Fire Department in Chicago’s western suburbs is prepared.

“All of our equipment is prepared for anything that can happen, no matter what the weather is,” said Elmwood Park Fire Chief Michael Terzo.

But Terzo also stressed that people, regardless of their willingness, should refrain from doing things that could end up requiring his department’s intervention.

“I wouldn’t recommend building a fire outside,” Terzo said.

Terzo said while it was great to enjoy the unseasonably warm weather, it was also important to enjoy it safely. This means increased caution – especially around piles of leaves and dry grass.

Cars should not be parked on or near such vegetation.

“They’re dry around the house,” Terzo said. “All you have to do is throw a cigarette butt or a match into a pile of leaves near your house and you’re off to the races.”

These conditions came with it Temperatures will reach the lower 80s in Chicago on Tuesday– and well on its way to breaking a heat record that is more than 20 years old.

The warm conditions, low humidity, south-southwest winds of 25 degrees with gusts up to 40 miles per hour and the fact that there has been no recent rain increase the fire danger.

“If it had rained yesterday, there would be no warning,” said Trent Ford, Illinois state climatologist, “because everything is wet, it’s not going to ignite.”

Ford said global warming plays a role in the high fire risk.

“A red flag warning is very similar to other types of weather warnings that we take seriously – such as tornado warnings, flash flood warnings, severe thunderstorm warnings and extreme heat warnings,” Ford said. “Climate change is actually having an impact increased frequency of fire weather – particularly this time of year.”

Climate Central has found that fire weather days like Tuesday have increased locally as the climate warms. Compared to 1973, there were an average of three more hot, dry and windy days in 2023.

“In certain weather conditions, a spark and a fire can spread very quickly,” Ford said.

The Elmwood Park Fire Department had not received any calls related to the red flag warning as of Tuesday afternoon. But down in Kankakee County, a small brush fire broke out in Pembroke Township, sending smoke billowing into the air.