As I sit by the window, watching the leaves begin to trade green for brown, I can feel the subtle shift in the air that signals fall’s arrival. But this year, something else is changing—not just here at home, but thousands of miles away across the Pacific Ocean. The waters there are cooling, and that means La Niña is making a comeback. It’s early in the season, but the atmosphere is already starting to respond.
So, what exactly is La Niña? In simple terms, it’s the “cool sister” to El Niño. During La Niña, sea surface temperatures in the central and eastern Pacific Ocean drop below normal, which in turn shifts global weather patterns. The Pacific jet stream tends to move northward, allowing colder air to dip farther south into the central United States while keeping the southern states a bit warmer and drier. Think of it as nature’s way of tilting the scales—just enough to change who gets the cold, the snow, and the rain.
This developing La Niña is expected to be weak to moderate, but even a subtle pattern like this can have big impacts over time. The last few La Niña events have been known to favor more active storm tracks across the northern U.S., cooler stretches in the Midwest, and even a few well-timed snow events that can sneak in when the moisture and cold air line up just right. Missouri and Illinois often find themselves sitting right in that weather “battle zone,” where mild southern air meets cold northern air, and that’s where things can get interesting.
Now, before we go making bets on a blizzard, let’s be realistic. A weak La Niña doesn’t guarantee a snowier winter, but it does increase the odds of pattern swings. One week may feel like January, the next like late March. We could also see stronger cold fronts and those classic Missouri temperature roller coasters, where it’s 70 degrees one afternoon and you’re scraping frost the next morning.
Another piece to this puzzle is how La Niña influences rainfall. Fall could start off on the drier side, especially across southern Missouri and Illinois. However, as winter deepens, the jet stream might start steering more systems across the midsection of the country. If that happens, our region could see a few stormy spells, with the potential for mixed-precipitation events—rain, sleet, and snow all trying to share the same stage.
When we talk about what to expect, it helps to look back at similar “analog” years—past seasons that saw similar ocean patterns. Some of the closest comparisons to what’s developing now include 2011-2012, 2017-2018, and 2021-2022.
The 2011-2012 winter started promisingly cold but quickly turned mild and dry, especially across Missouri. Snow lovers were left wanting more that year. In contrast, 2017-2018 brought a more traditional Missouri winter— cold snaps, bursts of snow, and plenty of gray days in between. Then there’s 2021-2022, which featured wild temperature swings and a few strong winter storms, including that memorable February snow-and-ice event that caused chaos across much of the region.
These analogs suggest we’re likely heading into another variable winter— periods of genuine cold mixed with stretches that feel more like early spring. If there’s one takeaway from the pattern, it’s that La Niña winters tend to keep us on our toes.
For now, though, enjoy the calm early fall while it lasts. The days are pleasant, the nights are crisp, and the leaves are putting on their annual show. But make no mistake—the Pacific is cooling, and that quiet shift will slowly ripple through the atmosphere as we move toward winter.
Whether you love snowflakes or dread the shovel, La Niña’s return means this season will have a little extra unpredictability. And from my window, that’s exactly what makes weather so fascinating.
