Amid a fall heat wave gripping much of the country, rare red flag warnings have been issued for Chicago and western Oklahoma, while firefighters reported they were gaining ground on a wildfire threatening homes in Colorado.

It may be late October, but the U.S. forest fire season It has reignited across the country as at least 11 active wildfires burned from California to New Jersey, officials said.

The National Weather Service issued a red flag warning for western, northwestern and northern Oklahoma, where firefighters are battling several wildfires near the cities of Cushing, Chickasha, Cimmaron City, Wellston and Seiling. The fires caused the evacuation of some homes and, according to Logan County Emergency Management, destroyed “some” residences in Logan County.

Oklahoma’s largest active fire 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 Tuesday night, officials said.

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

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

The greatest fire danger is forecast Wednesday for the southern plains, including Oklahoma, Kansas and Texas.

Dangerous fire conditions are also being seen in parts of New Mexico, where officials issued a “ready status” advisory for residents of Lake Bonito in Lincoln County to be prepared to evacuate if the Blue Front Fire, which started on Monday and had burned 270 acres by Tuesday it gets worse.

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

“The reason this has been so successful and the reason we’re here 72 hours later and not seven days later is because of all the work that was done that first day, that first night,” Mikesell said.

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

Mikesel said firefighters on the front lines faced winds over 50 mph and gusts over 60 mph Tuesday, but made significant progress in containing the fire.

Mikesel, about 150 firefighters were fighting the fire on Wednesday.

The Teller County Board of Commissioners declared a local disaster emergency. A structure had been destroyed Monday night, county officials said in an update.

No injuries have been reported.

The sheriff’s office received and requested assistance from multiple agencies in the region to combat the fire, Mikesell said.

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

Elsewhere, a red flag warning was issued this week in Massachusetts, where firefighters continue to battle a 400-acre wildfire near Salem. Fire crews are also battling another wildfire that started Sunday and consumed at least 250 acres near Middleton, Massachusetts.

According to the National Interagency Fire Center, at least 11 active large fires across the United States have burned more than 1 million acres. According to the center, at least 4,000 forest firefighters were fighting the flames.

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

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

Temperatures rose to near 80 degrees in Minneapolis on Monday.

This week, the NWS also issued a rare red flag warning for New York City, which has had no 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, burned nearly 80 acres, authorities said.

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

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