The National Weather Service’s Climate Prediction Center is growing more confident in the emergence of a La Niña weather pattern later this year, and it would have significant impacts on fall and winter weather in the Chicago area.
Chicago winters can be unpredictable, but that doesn't stop the predictions from rolling in.
With fall now officially underway, attention has started to turn to the season ahead and what could come next.
While most Chicago winters will see brutal cold and some snow, just how cold and how much snow can vary dramatically year over year.
Still, there are some factors that can give some insights on what to expect for the seasons ahead. The only problem is, many of the predictions appear to have conflicting thoughts.
Here's a look at what to know:
Farmer's Almanac prediction for 2024-25 winter season
Recently, the Farmer’s Almanac released its winter weather forecast for the upcoming year, and predicted cold and dry conditions for the area around the Great Lakes, including northeastern Illinois and northwest Indiana.
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The forecast also called for snowy conditions along the Mississippi River, and cold and snowy conditions in southern Illinois and southern Indiana.
How accurate are these predictions?
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The publication claims a success rate of 80% with its predictions, though many studies have contested that figure over the years.
Many meteorologists dispute the accuracy and the methodology employed by the publication. One such study, conducted by the University of Illinois and cited by Popular Mechanics, holds that the Old Farmer’s Almanac is only correct 52% of the time, which essentially represents the odds of a coin flip landing on either heads or tails.
What about the National Weather Service?
The National Weather Service’s Climate Prediction Center only has an outlook that runs through the conclusion of meteorological fall, which ends on Nov. 30. That outlook is leaning toward above average temperatures in the Chicago area during that time, and about equal chances of either wetter or drier conditions than normal.
Where the forecast really comes into play is when it comes to the emergence of a La Niña pattern. The NWS says there is a 74% chance of La Niña emerging during the first two months of winter in December and January.
La Niña patterns occur when sea-surface temperatures along the equator in the Pacific Ocean are unusually cold. Trade winds then grow in strength, pushing warmer water toward Asia, which then allows cool water to rise to the surface near the west coast of the Americas.
Those cool waters push the jet stream northward, drawing in moisture that pelts the western United States with rain. Other parts of the country are also impacted.
In the Chicago area specifically, winters associated with a strong La Niña pattern tend to have warmer temperatures, but also to have more snowfall, with more frequent blizzards and winter storms impacting the area, according to Illinois’ state climatologist.
The publication did caution that impacts can vary widely based on the strength of the pattern, and that there are fewer La Niña’s to base predictions off of.
A new La Niña forecast is expected to be released later this week.
What else to know?
The NBC 5 Storm Team stressed that predictions this far out are challenging and often lack a lot of information.
NBC 5 Storm Team Meteorologist Kevin Jeanes looked back at the last 10 years of weather data for Chicago to gather insights for winter.
The first snowfall has been all over the place, especially in recent years. Last year was Chicago’s warmest winter in 92 years, but it still snowed on Halloween.
The 30-year average for the first measurable snow (0.1” or greater) was Nov. 18; however, last year’s was Oct. 31, and in 2021 it was Dec. 28 - another indicator of how unpredictable it is in the long-term.
It’s worth noting that La Niña has a 74% of being present this November to January. Depending on its strength, that could bring a wetter and colder winter for Chicago, Jeanes said.
