- El Niño is expected to play a role in affecting winter temperatures.
- This generally means milder winters in the northern United States and colder, wetter weather in parts of the South.
- But there are some important factors that could change the forecast for this winter.
The U.S. winter could be affected by El Niño, according to an outlook released Thursday by IBM's The Weather Company and Atmospheric G2.
Warmer weather is expected in parts of the North: A strong El Niño this winter is typically associated with above-average temperatures across much of the northern United States, which also means winter temperatures are typically slightly below average in parts of the southern United States.
In the map below, temperature patterns are often the theme of this winter's outlook.
Temperature patterns are expected to dominate throughout the three-month period from December to February.
The outlook is for an overall three-month trend, so each region of the country will experience warmer or cooler periods than what is shown above.
With that in mind, let's break down the forecast month-by-month and follow up on some important factors that could change this outlook.
Winters are likely to be warmer than average in the Great Lakes, Northeast, and Mid-Atlantic: Those in the Northeastern United States hoping for cold December weather to prepare for the holidays may be out of luck this year. Cities such as Washington, Philadelphia, Chicago, Boston and New York are all currently experiencing well-above-average December temperatures.
Temperatures should be very close to normal across the western to southeastern United States.
(Further enhance your forecasts with our detailed hourly breakdown for the next 8 days – only available on our website Advanced professional experience.)
December Temperature Outlook.
It's likely to be cooler in the Southeast as the new year begins: A hallmark of El Niño is cool, wet weather in the middle of winter in parts of southern states, such is the outlook from the lower Mississippi River into Georgia and parts of the mid-Atlantic. There's no guarantee, but the combination of these ingredients could increase the likelihood of snow and ice in parts of the region.
The West, Northern Plains and Northeast have the highest chances of warmer than average January temperatures.
January temperature outlook.
The last month of winter may see cooler conditions in the east and warmer conditions in the west and plains: In February, the warmest core relative to average temperatures is likely to be from the Northwest to the northern Plains.
However, much of the East is likely to experience colder-than-normal temperatures, with Florida and southern Georgia most likely to see below-average temperatures.
February temperature outlook.
These factors could change winter forecasts
How much will El Niño's warm Pacific waters react to the atmosphere? Dr. Todd Crawford, vice president of meteorology at Atmospheric G2, said the current lack of atmospheric response in the tropical Pacific means Arctic air intrusions may be more common than during typical strong El Niño winters.
Will the polar vortex weaken later in winter? When the polar vortex weakens, cold air normally trapped in the Arctic may spill over into parts of Canada, the United States, Asia and Europe as the jet stream becomes more choked by a sharp southward meander, pushing longer-lasting cold Air is transported southward to mid-latitudes.
Crawford said there's a good chance the polar vortex will weaken by mid-winter, which means the U.S. faces the risk of colder weather in the second half of winter.
An example of a weak polar vortex in winter.
The Weather Company's primary journalism mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily reflect the views of our parent company, IBM.
