El Ni単o returns: How that could affect this winter in Iowa
Winter is coming and for the first time in a few years, El Ni単o is coming with it.
What is El Ni単o?
El Ni単o and La Ni単a are the two phases of the El Ni単o Southern Oscillation climate pattern, which originates in the eastern Pacific Ocean along the equator.
During El Ni単o, the trade winds blowing from the east weaken. This allows warm water to build up off the coast of South America.
The warmer water heats the air, affects pressure and moisture levels in the atmosphere, and alters weather around the globe.
Off the west coast of North America, El Ni単o strengthens the Pacific jet stream, which then carries more moisture across the southern US. To the north, the polar jet stream shifts closer to the Arctic. This increases the odds of warmer-than-average winters in the northern US and Canada.
El Ni単o and Iowa
Iowa, being a northern state, is more likely to be warmer than average during an El Ni単o winter.
NOAA projects this coming El Ni単o to be strong, which makes warmer than normal temperatures even more likely.
Four of the last five strong El Ni単o winters in Des Moines have been considerably warm and at least somewhat less snowy than average.
Other factors matter as well
While El Ni単o is a major climate pattern, it's just one of many that affect us. Sometimes, these patterns conflict with each other.
For example, the 2009-2010 winter happened during a strong El Ni単o, but central Iowa was colder than normal and recorded one of its snowiest winters on record.
Our current El Ni単o is the first since 2019. The last strong El Ni単o ended in 2016.