How The Start Of February Will Be Different Than January, Especially In The South

New Month New Pattern, Especially In The South

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F​ebruary begins this weekend and temperatures to start the new month are shaping up to be different than what we saw much of January east of the Rockies, especially in the South.

J​anuary has been significantly colder than average. Every location east of the Rockies had temperatures that were below average in the first 25 days of the month, as the analysis below using data from NOAA's Climate Prediction Center shows.

Much of the South, Ohio Valley, mid-Atlantic and parts of the Plains have had the most persistent cold, running 6 or more degrees below the Jan. 1-25 average. This is calculated by combining the highs and lows each day through that time.

I​n fact, a few dozen locations, mainly in the South and East, were on pace for a top 10 coldest January, as noted by senior meteorologist Jonathan Erdman.

End of January and F​ebruary's first few days are flipping the frigid script for many. The weather pattern has already transitioned to a milder one for many east of the Rockies as we end January. That's likely to persist through the upcoming first weekend of February, which includes Groundhog Day Sunday.

Parts of the South will see 60s and 70s, and upper 40s or 50s are possible in the Midwest and mid-Atlantic.

W​hile cold fronts will tame the milder temperatures after this weekend in the northern tier, the Southeast will likely stay mild for some time to come, as indicated by the long-term outlook from NOAA's Climate Prediction Center.

A weather pattern shift is the cause of this change. For much of January, the jet stream has taken repeated sharp southward plunges over the central and eastern states, unloading bouts of arctic air into those regions. That includes last week's round of bitter cold, which had an source region from near Siberia.

T​he jet stream has undergone a shift as we close out January and enter February to a more flat, west-to-east orientation, as shown below. This allows milder air to return northward and effectively "walls off" arctic cold from spilling into most areas east of the Rockies.

T​hat said, not all regions will bask in a mild start to February. Parts of New England, the Northern Plains and Northwest might be chilly to start the month.

Chris Dolce has been a senior meteorologist with weather.com for over 10 years after beginning his career with The Weather Channel in the early 2000s.