Amid a fall heat wave sweeping much of the country, rare red flag warnings were issued for Chicago and western Oklahoma as firefighters said they gained the upper hand on a blaze forest threatening homes in Colorado.

It may be late October, but the United States wildfire season resumed across the country as at least 11 active U.S. wildfires burned from California to New Jersey, officials said.

A Red Flag Warning has been issued by the National Weather Service for western, northwest and northern Oklahoma, where firefighters are battling several wildfires near the towns of Cushing, Chickasha, Cimmaron City, Wellston and Seiling. The fires caused the evacuation of some homes and, according to Logan County Emergency Management, destroyed “a few” residences in Logan County.

The largest active fire in Oklahoma is the Rush Fire, which has burned more than 12,000 acres in the Wichita Mountains National Wildlife Refuge, about 70 miles southwest of Oklahoma City. The Rush Fire, which started Thursday, was 48% contained as of Tuesday evening, officials said.

The NWS also issued an alert warning for the Chicago area on Tuesday, saying in an advisory: “Critical fire weather conditions are currently occurring or will occur shortly.” The temperature soared to 82 degrees in Chicago on Tuesday, tying a daily heat record.

Gusty winds and extremely dry conditions helped spread a grass fire that broke out south of Chicago on Tuesday, closing part of Interstate 74 due to smoke, officials said.

On Wednesday, the highest fire danger is forecast for the Southern Plains, including Oklahoma, Kansas and Texas.

Dangerous fire conditions are also being observed in parts of New Mexico, where authorities have issued a “Ready” advisory for residents of Bonito Lake in Lincoln County to prepare to evacuate if the fire in Blue Front, which started Monday and had burned 270 acres by Tuesday, is getting worse.

The Highland Lake Fire, which broke out around 4 p.m. Monday and burned 166 acres near the town of Divide, was 80% contained as of Wednesday afternoon, according to Colorado firefighters. All evacuation orders have been lifted, Teller County Sheriff Jason Mikesell said during a news conference Wednesday.

“The reason it was such a success and the reason we’re here 72 hours later and not seven days later is because of all the work that went into that first day, that first night ” Mikesell said.

The sheriff said investigators investigating the cause of the fire focused on a structure that was destroyed by flames. He said investigators suspect the fire was “human-caused,” but it remains unclear whether the cause was accidental or criminal.

Mikesel said firefighters on the front lines faced winds of more than 50 mph and gusts of more than 60 mph Tuesday, but were able to make significant progress in containing the fire.

Mikesel, about 150 firefighters were battling the blaze Wednesday.

A local disaster emergency has been declared by the Teller County Board of Commissioners. A structure was destroyed Monday evening, county officials said in a statement.

No injuries were reported.

The sheriff’s office was called upon and received assistance from several area agencies in battling the fire, Mikesell said.

The NWS has issued alert warnings for dangerous fire conditions in the Divide area.

Elsewhere, an alarm was sounded this week in Massachusetts, where firefighters continue to battle a 400-acre brush fire near Salem. Fire crews are also battling another brush fire that started Sunday and has consumed at least 250 acres near Middleton, Massachusetts.

At least 11 large active fires in the United States have burned more than 1 million acres, according to the National Interagency Fire Center. At least 4,000 firefighters were battling the blazes, according to the center.

Wildfires were also burning in Michigan, Wyoming, Utah, Oregon and New Jersey.

The elevated risk of wildfires comes amid record temperatures across the country. High temperature records were tied or broken in dozens of cities Monday, including Oklahoma City; Kansas City, Mo.; Wichita, Kansas, Minneapolis, Minnesota; Witchita Falls, Texas; and Austin, Texas.

Temperatures climbed to nearly 80 degrees Monday in Minneapolis.

This week, the NWS also issued a rare red flag warning for New York City, which has not received any measurable rain in about a month.

In New Jersey, Governor Phil Murphy issued a Draft Watch, advising businesses and residents to conserve water.

A wildfire that broke out last week in the drought-ravaged area near Rockaway Township in Morris County, New Jersey, has burned nearly 80 acres, officials said.

On Monday, the NWS in Philadelphia and New York City issued a special weather statement warning of a high risk of wildfire spread.

According to the release, “vegetation remains very dry and could potentially fuel fires. These conditions will favor the spread of any fires that ignite, which could quickly become difficult to control.”