El Niño or La Niña may be present, or not, at any time of the year, but depending on the season, some regions could be threatened by worse weather. This fall, La Niña is slowly developing, and this shift in the pattern is expected to last at least through February 2025. Scientists are not expecting a strong La Niña event, but even a weak La Niña during winter could mean a different type of winter for the South.
Scientists already know that the winter season is the season that signals the most warning as it is. Having a La Niña present exacerbates the warming pattern, especially in areas where the heat has been relentless in recent months and years.
What is La Niña?
El Niño Southern Oscillation, ENSO, is a phenomenon that occurs in the tropical Pacific Ocean. When average water temperatures are above average, it dictates that an El Niño is present; when temperatures are below average, La Niña is present. These phenomena not only bring cooler or warmer-than-average temperatures but also create shifts in the wind shear around the globe and shifts in the position of the jetstream, which bring significant changes in weather patterns while one is present. La Niña events typically occur every 3 to 5 years, but the interval between events can vary from 2 to 7 years.
How does La Niña affect the winter?
La Niña present in the winter months usually displaces the jetstream more northward; this tends to bring drier and warmer than normal conditions during its duration. There is a 60% chance for La Niña to develop through November, and its chances of developing go up during the winter. The jetstream northward displacement keeps storms moving across northern latitudes and less frequent more south. Fewer storms moving across the South means the weather pattern will stay drier, and with fewer storms that bring clouds, temperatures tend to stay warmer. Water temperatures also tend to stay warmer than average across the Gulf and eastern Atlantic.
This winter's La Niña will likely be weak, so expect more variations to the "warmer and drier" usual outlook under an average or strong La Niña across the Southeast.
La NiñaWhat does it mean for South Carolina?
When a La Niña is present in winter, the season tends to stay warmer and drier than usual. This pattern was present during the winter of 2016-2017. These months, temperatures stayed warmer than average. Winters across South Carolina, on average, are mild, with temperatures around the mid-30s in the mountains and around the low 50s in the Midlands.
Having La Niña does not mean we will not receive cold snaps. There will be storms and some cold fronts, but they will be less frequent and perhaps less intense. Once the season is over, we will look back and notice the overall trend was warmer than average.