The Yukon and Western provinces could be looking at a warmer winter next season as scientists around the world have officially declared the formation of an El Niño weather pattern.
On June 11, the US National Oceanic and Atmospheric Administration (NOAA) declared an El Niño year following earlier predictions by the World Meteorological Organization and the United Nations.
According to research scientist Bill Merryfield of Environment and Climate Change Canada (ECCC), the formation of an El Niño and its sister weather pattern La Niña is driven by the natural warming and cooling cycle of waters near the equator in the Pacific Ocean.
Merryfield says it’s the emergence of warmer waters in the Pacific that drives El Niño formation.
“When this [warming] happens, and the El Niño sets in, the changes in these ocean surface temperatures cause shifts in wind patterns,” he explains.
These shifting wind patterns can alter the path of the polar jet stream, which typically flows west to east across Western Canada and the northern United States and acts as a barrier to warmer tropical air. Merryfield says that an El Niño, however, disrupts this pattern, pushing the polar jet stream northward.
“That is what brings us generally fewer cold air outbreaks and milder than usual temperatures,” says Merryfield.
This year’s El Niño is also particularly exceptional for its strength, leading some forecasters to call it a “super El Niño,” according to Merryfield.
He says these “super El Niños,” while rarer, aren’t unheard of, and the last one occurred in 2015.
“El Niño, like many weather phenomena, comes in a range of strengths,” says Merryfield. “A so-called super El Niño is also classified as a very strong El Niño and that’s caused when the water in the tropical Pacific exceeds two degrees of warming for a certain period”.
Merryfield says that the last super El Niño brought with it an extraordinarily warm winter in 2015-2016, with temperatures averaging 6-8 degrees warmer than a typical winter.
While a mild winter on the horizon might be welcomed by some Yukoners following the punishing cold of 2025-2026, Merryfield says the impacts of El Niño could last beyond just the winter. Strong El Niño events are also typically associated with lower precipitation levels and an earlier spring, followed by extraordinarily warm summers.
“One aspect of sort of more the global scale is that El Niño events tend to pour a lot of heat from the ocean into the atmosphere”, says Merryfield. “Because of this, the years following an El Niño are often the warmest globally on record, so we do anticipate with pretty high likelihood that 2027 will set a new global temperature record”.
Contact Noah Korver at noah.korver@yukon-news.com