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Scientists say a “super” El Niño is likely to cause a mild winter to many parts of the central U.S. — and may bring relief to some states experiencing drought.
The naturally occurring climate pattern happens every two to seven years when subtropical trade winds blow warmer water towards America’s West Coast.
But this year’s El Niño is forecasted to be the strongest on record dating back to 1950, according to the National Oceanic Atmospheric Administration. It’s driven by record-high temperatures in the Pacific Ocean.
El Niño is known to cause drier and warmer-than-normal winters for much of the Midwest and Great Plains, while creating wetter and slightly cooler conditions across the nation’s southern states.
“The strength of the El Niño doesn't guarantee those conditions. And it doesn't mean that those impacts will be greater,” said Gary McManus, the state climatologist in Oklahoma. “It generally means that those impacts are more likely.”
McManus said the U.S. could start to see those changes as early as September, but conditions usually peak November through January.
El Niño weather patterns have been getting stronger in recent cycles, according to research from the University of Michigan.
Climate change could be contributing to the intensity, said Sylvia Dee, a climate scientist at Rice University.
She said the way climate change and El Niño interact are still being studied, but data shows a higher frequency of extremely large and hot warming events since the late ‘90s.
“The total impact on the characteristics of El Niño events is still unknown,” Dee said. “But what we do know is if you heat up the bathtub and then you pour some more hot water in it, it's going to get hotter.”
Dee said that the central U.S. hasn’t been largely impacted by El Niño weather events in past years. But because of the projected intensity of this El Niño, higher temperatures in the Midwest are likely.
Mild weather in the Midwest
States in the upper Midwest – including Michigan, Wisconsin, Minnesota and the Dakotas – are likely to experience temperature averages that are 2 to 4 degrees higher than normal, according to Illinois State Climatologist Trent Ford.
Other states in the region, such as Nebraska, Iowa, Missouri, Illinois, Indiana and Ohio, can expect average winter temperatures to increase by 1 to 3 degrees.
“I know 1 to 4 degrees doesn't seem like a lot, but when we're averaging a lot of time and especially when that's the entire seasonal average, that does really paint a pretty strong picture of a response for milder winters,” Ford said.
Those warmer temperatures will likely cause snow to melt faster, which may create less snowpack across the region, said Ford.
That might hurt winter recreation activities that rely on snowpack, like cross country skiing and snowmobiling.
But, Ford said a “mild” winter does not eliminate the possibility for snow or winter storms.
“Any individual winter storm event will be more of a function of where the jet stream is,” Ford said. “Which yeah, could have an El Nino signature, but is more determined by kind of the weather conditions at that time.”
For states neighboring the Great Lakes, there might actually be larger storms, according to Jen Brady, a senior data analyst for the nonprofit Climate Central.
“If we have a warmer winter, that means the lakes aren't going to freeze,” Brady said. “And so when there are conditions set up for snow, it could be even heavier because you have a warm lake to fuel that snowstorm.”
Lake-effect snow has become more common as the climate changes, Brady said, so an El Niño weather pattern could intensify that.
A warmer winter could be bad news for farmers who grow fruit and berries in the region, Ford said. Higher temperatures could mean trees and bushes start flowering too early.
“It could put them at a higher risk of spring freeze damage, even if we don't get like a late spring freeze,” said Ford.
Warmer conditions can also make it tricker for farmers to deal with pests.
“Sometimes we can see those milder winters mean that those insect pests that come up from the south especially can get up and establish more quickly,” Ford said.
Drought relief in Oklahoma and Texas
Meanwhile, in states such as Oklahoma and Texas, climatologists expect wetter weather and slightly cooler temperatures.
“Statistically speaking, if you were going to make a bet, you would put your money on wetter than normal conditions just from the past El Niño's and what's occurred during those El Nino's, especially the very strong El Niño's,” said McManus, the Oklahoma state climatologist.
With more moisture-laden air coming into the southern U.S., Texas and Oklahoma may experience more storms, according to Dee, the climate scientist from Rice University.
“The more moisture, the more rainfall, the more you tend to have what's called atmospheric instability, which leads to the development of thunderstorms,” Dee said.
Additionally, any arctic blasts of air that may dip south and mix with the warm, moist air has the potential to create more severe weather.
The likely rain and cooler temperatures could bring relief to the region after years of severe drought. McManus said Oklahoma farms desperately need more precipitation.
“We're really coming up on the important season for winter wheat,” McManus said. “Farmers would like to plant, but the soil is so dry that we do need that rainfall to come on very quickly.”
McManus said precipitation trends from El Niño could start as early as this month, but it’s more likely later this fall.
Although scientists can predict how an El Niño winter may look like, it’s not guaranteed, McManus said.
“Each one of them tends to have its own particular impacts,” McManus said. “El Niño and La Niña are only a portion of what impacts our weather or influences our weather.”
This story was produced in partnership with Harvest Public Media, a collaboration of public media newsrooms in the Midwest and Great Plains. It reports on food systems, agriculture and rural issues.
