An unusually warm autumn is giving way to a sharp weekend chill across much of the United States. More than 270 million people are experiencing below-average temperatures as Canadian air pushes south, reaching even Florida.

The change follows a departing nor’easter and a southward bend in the polar jet stream, which has opened a path for colder air to spread across the eastern states. According to the FOX Forecast Center, frost and freezing conditions are expected across more than 30 states east of the Rocky Mountains.

For Southeast residents, the shift has been particularly noticeable. After afternoon temperatures reached the 70s earlier in the week, weekend readings fell into the 30s and 40s. More than 30 million people across six southern states were under cold alerts Saturday morning.

Florida also felt the cooldown. Orlando and Tampa recorded Saturday morning temperatures in the mid-to-upper 40s, while northern Florida and the Panhandle saw readings ranging from the upper 30s to the lower 40s.

Farther inland, the cold brought the season’s first freeze to parts of the Midwest and the Mississippi and Tennessee valleys. Overnight temperatures in Omaha and Kansas City dropped into the mid-to-upper 20s, delivering their first hard freeze of the season.

The late arrival of freezing weather highlights how long autumn warmth has lingered. Omaha came close to matching its latest first-freeze record, shared by 1915 and 2015. Chicago and Detroit were also expected to experience their first below-freezing temperatures of the season during the weekend.

The broader climate backdrop includes a strengthening El Niño. In its November 12 update, NOAA forecast that strong-to-very-strong conditions would likely persist through January–March 2027. That outlook does not mean every region will experience the same weather effects.

The current chill, however, is expected to ease relatively quickly. The original report cites NOAA’s outlook for warmer temperatures to return by midweek, making this a brief interruption to the prolonged autumn warmth.

The article, published by the New York Post on November 15, 2026, attributes the weather details to the FOX Forecast Center. All temperatures are in Fahrenheit.