The eastern US has been gripped by an Arctic freeze. That’s about to change

By Andrew Freedman, CNN

(CNN) — The US is a nation divided, with frigid conditions, snow and ice entrenched east of the Rockies all the way into Florida, and record warmth and paltry snowfall in the West.

The dichotomy has lasted weeks and is finally about to shift – but only after one more major blast of Arctic air this weekend for the East.

This divide sharpened in recent days; parts of the West are seeing late-springlike warmth, with temperatures 20 to 30 degrees Fahrenheit above average, while parts of the East are set to experience their coldest temperatures so far this season this weekend.

In the warm category is Great Falls, Montana, for example. Residents there are seeing five straight days with a high temperature exceeding 60 degrees Fahrenheit this week, which would be the warmest five-day stretch on record for the month of February.

And in Los Angeles, the temperature on Wednesday reached a record high of 88 degrees, which beats their typical highs in July and August.

The cold East, warm West pattern comes courtesy of the contortions of the jet stream, and it is noteworthy for being so pronounced and enduring. Washington, DC, for example, saw its sixth longest stretch of consecutive hours below freezing from Jan. 24 to Feb. 2. Many other cities also saw such stretches that ranked in their top 20 longest on record.

The warmth and lack of snow in the West have been features of this winter so far, pre-dating the cold in the East. But it is the contrast between the temperatures dividing this country that is so striking on weather maps.

At one point last weekend, Juneau, Alaska, was warmer than central Florida.

The warm and dry conditions in the West can be traced to a persistent bulge or ridge in the jet stream that has shunted storms and colder air to the north. Downstream, though, a large dip in the jet stream, or trough, has dug its claws in, bringing wave after wave of Arctic air southward, along with conditions that are ideal for forming powerful winter storms.

Many spots in the Carolinas and even Atlanta picked up more snow during January than Salt Lake City did. Only a tenth of an inch fell there during the month, far below the average of 12.7 inches.

For those still shivering in the East, and people tired of the warm and dry conditions in the West, a pattern change is finally in sight.

The western ridge is projected to break down, and that will allow the pattern to get moving, allowing the milder air to move to the east and finally clear the way for some Pacific storm systems to move into the West.

But before that happens, the coldest air of the winter so far will invade the Northeast and Mid-Atlantic states this weekend into early the following week. About 50 cold temperature records may be set this weekend, where temperatures will be in the single digits but feel double-digits below zero.

With winter being the fastest-warming season in the US, cold records are few and far between, particularly monthly and all-time cold records. This is reflected in data comparing daily warm and cold records during the past several days to the year as a whole.

During the peak of the arctic blast stretching from the last week of January into the beginning of February, cold records outpaced warm records by more than two-to-one in the Lower 48 states. But that is not the case when looking at 2026 so far, however, where warm records have been around 1.5 times more numerous than the cold records that we have seen since January 1st.

In a rapidly warming world, warm temperature records have increasingly outpaced cold records.

So why has it been so cold in the East? Forecasters are placing some of the blame on the Arctic Oscillation, a broad upper-level pattern that shows up in pressure differences between the Arctic and the mid-latitudes.

“One factor that has likely played a role is the Arctic Oscillation (AO), which characterizes how wavy the jet stream is,” said Laura Ciasto, an atmospheric scientist with NOAA’s Climate Prediction Center “When the AO is negative, the jet stream is more wavy with lobes dipping down over the US and bringing colder Arctic air with it,” she said.

“The AO has been negative for over a month now, which is impressive because it usually doesn’t stay in one phase for that length of time. So something else could be influencing it to stay in the negative phase,” she said, pointing to events elsewhere, notably the tropical Pacific, as also playing a role in influencing recent weather patterns over North America.

CNN meteorologist Brandon Miller contributed reporting.

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