Ten days ago, Chicago reached 54 degrees. Patios opened. Joggers shed layers with reckless confidence. A man in Lakeview was photographed eating a salad outside, in shorts, at a table that still had frost on the legs. The city, in its infinite capacity for self-deception, declared it spring. Some residents reportedly put their heavy coats in storage. Others simply looked at the sky, felt the sun on their faces, and allowed themselves, for one trembling afternoon, to believe that the worst was behind them.

Today the high is 27°F. The wind chill is 14. Lake Michigan, which ten days ago was reflecting sunlight like something out of a tourism brochure, is now throwing four-foot waves against a shoreline crusted in fresh ice. The patio furniture has been retrieved. The jogger is wearing a balaclava. The man with the salad could not be reached for comment, though a neighbor reports he has “not been the same.”

This is, of course, entirely normal. The National Weather Service office in Romeoville confirmed Tuesday morning that a 27-degree temperature swing over a ten-day period in mid-March falls squarely within historical norms for the Chicago metropolitan area. “This is what March does,” said meteorologist David Pruitt, with the resigned tone of a man who has explained this every year for two decades. “March is not a month. March is a negotiation. The atmosphere is still deciding what season it wants to be, and Chicago is where it comes to argue.”

The data bears this out with almost comic precision. According to NWS records, Chicago’s average high on March 7 is 43°F and its average high on March 17 is 46°F, meaning both last week’s warmth and this week’s cold represent significant departures from the mean — in opposite directions, within the same calendar page. The city has, in effect, experienced a complete round trip through hope and despair without ever leaving the same month.

The psychological toll of this pattern is well-documented, if largely unquantified. Dr. Ellen Varma, a clinical psychologist at Northwestern who studies seasonal mood fluctuation, describes the phenomenon as “thermal whiplash” — a state in which residents who have emotionally committed to spring are forced to recalibrate their entire outlook within days. “The 54-degree day is almost cruel in retrospect,” Varma said. “It creates a reference point. Now every cold day isn’t just cold — it’s cold relative to the day you thought it was over. That’s a different kind of cold. That’s a betrayal.”

On the lakefront Tuesday morning, the evidence of this betrayal was everywhere. The Lakefront Trail, which last week hosted its first tentative cyclists and dog walkers of the season, was nearly deserted. A single runner moved north past Fullerton, head down, face wrapped in a fleece gaiter, exhibiting the grim determination of someone who has made a commitment to outdoor exercise and will honor it regardless of whether the outdoors appears to want them there. Ice had formed overnight on the path’s drainage grates. The benches, briefly liberated from winter’s grip, were glazed with frost.

And yet there is something almost clarifying about this moment — the annual reminder that March in Chicago is not a linear progression toward warmth but a series of provocations. The city gives you one warm day to remind you what you’re waiting for, then takes it back to remind you that you are not in charge. Pruitt, the meteorologist, puts it more plainly: “People see 54 degrees in early March and think the corner has been turned. The corner has not been turned. There are several more corners. Some of them go backwards. That’s the corner situation.”

The forecast for the rest of the week offers modest relief: low 30s Wednesday and Thursday, climbing to 41 by Saturday — a temperature that, two weeks ago, would have been unremarkable, but which now, in the aftermath of both the false spring and the correction, will likely be greeted with the cautious optimism of a city that has learned, once again, not to trust anything that happens before April. The patio furniture, for now, remains indoors. The heavy coats have been un-stored. And somewhere along the lakefront, Lake Michigan continues its ancient, indifferent argument with the season, unbothered by the humans on its shore who briefly thought they had won.