In Chicago, It’s Summer in February

February is usually frigid perfection for the ice rink at Millennium Park in downtown Chicago, a favorite winter stop for tourists and local families that stands in the shadow of the reflective sculpture known as the Bean.

On Tuesday morning, the rink was melting.

Under an intense sun and 70-degree air temperatures, water slowly trickled out of the empty rink, flooding the surrounding concrete. Baby birds splashed happily in the pools of water. The ticket counter was abandoned, apparently closed for the day.

Winter in Chicago — or the lack of it — reached an unnerving peak on Tuesday, when the city came close to breaking a 48-year-old high-temperature record.

But forecasters said that the balmy spell was not going to last. They pointed out that the mild conditions in Chicago and around the Midwest this week were extreme, not just for the warmth but also for what would follow.

That was likely to include plunging temperatures dropping into the 20s, blustery northwest winds gusting up to 40 miles an hour and potentially dangerous storms, including tornadoes.

Still, for most of Tuesday, Chicago looked and felt like summer: Apartment windows were pushed open to catch the warm breeze. Restaurants set up tables and chairs on sidewalks for al fresco lunch service, a rare sight in a Chicago February.

The lakefront was teeming with runners, cyclists and couples strolling hand in hand.

“We expected it would be very cold,” said Ana Marchal, 41, a doctor from Cádiz, Spain, who arrived in Chicago on Monday for a vacation with her husband, Rolf Hartmann.

They had figured on spending their holiday indoors, by shopping, visiting museums or attending Blackhawks and Bulls games.

Instead, they found themselves walking on the beach, looking delighted and a little perplexed. They stopped to take a selfie by Lake Michigan, which is usually icy and forbidding this time of year.

“How beautiful,” Mr. Hartmann said. “It looks like the sea.”

“It’s colder in Spain than here,” Dr. Marchal said.

Others found the weather ominous.

Shailaja Chandrashekararao, a social worker who moved from India to Chicago last year, had just finished a 10-kilometer jog downtown. She said she would have liked to keep running.

“It was too hot,” Ms. Chandrashekararao said, tugging at the sleeve of her neon-orange workout top.

Climate change has made summers in India unbearably, dangerously brutal, she said, making Chicago something of a weather haven. But the city’s mild winter, on the heels of the warmest year on record in 2023, felt eerie and unpredictable.

“I’m not enjoying this,” she said. “It’s quite crazy, actually.”

Temperatures are also rising across the Midwest, in part because of human-caused climate change, according to the 2023 National Climate Assessment, the government’s premier compilation of scientific knowledge on the effect of human-caused warming. The report also noted that the warming posed significant economic risk to the region.

The June-like temperatures will be one factor in producing severe thunderstorms in the Chicago area Tuesday evening and overnight. Some of the storms could spawn tornadoes, forecasters said, with the most likely area stretching from Missouri across southern Illinois and northern Indiana to Michigan. Tornadoes that occur after dark can be more dangerous because so many people are asleep.

The main threat from the storm system, though, will be hail, possibly including hailstones as large or larger than hen’s eggs.

Unseasonably high temperatures across the Great Plains, along with high winds, were propelling wildfires in Nebraska and Kansas, which were still a threat on Tuesday after forcing evacuations this week. Wildfires were also raging across the Texas Panhandle.

And from Tuesday to Wednesday in Chicago, the temperature could drop by nearly 60 degrees, according to David King, a meteorologist for the National Weather Service.

“It’s remarkable,” he said, noting that the last time the city saw such a rapid temperature drop was in the 1990s. “It’s just a wild time for weather here in Chicago.”

A normal daytime high in Chicago at this time of year is about 40 degrees. According to the National Oceanic and Atmospheric Administration, only 4.3 percent of the Great Lakes’ surface is ice-covered, well below the average.

The unseasonably warm and dry winter has affected tourism in the region, especially in Michigan, Wisconsin and Minnesota, where industries that depend on snow have suffered. Gov. Tony Evers of Wisconsin announced last week that many businesses in northern Wisconsin — ski slopes, restaurants and snowmobiling tours, for example — may be eligible for a federal disaster loan program if they have incurred losses from the mild winter.

The mild day on Tuesday was already feeling familiar, said Charles Jones, who manages maintenance work for a residential building in downtown Chicago.

Mr. Jones spent his break standing outside in short sleeves, as people walked their dogs in the sunshine. He has lived in Chicago his whole life, he said, and was used to the harsh winters that the city is known for. But it was hard to remember the last winter where the cold had felt truly brutal — “a few years ago, maybe,” he shrugged.

This winter has been a lot like the one before, Mr. Jones said, without very much snow or many cold, icy days. In the last few months, he said, he has only had to salt the sidewalk twice.

“I don’t trust this weather, though,” he said. “You know we’re going to get a little snow before winter is done. It’s Chicago. It can be 70 and then jump down to 30.”

Judson Jones contributed reporting.