A strengthening El Niño event in the Pacific Ocean is driving extreme sea surface temperature anomalies of up to 11 C, according to Lindsey Long, a meteorologist with the ENSO team at the Climate Prediction Center (CPC) in the U.S. Every indicator shows the El Niño-Southern Oscillation is continuing to build, disrupting global weather patterns and setting the stage for a potentially mild winter across Western Canada.
Pacific Ocean Sea Surface Temperatures Fuel Strong ENSO Cycle
The current fluctuation in the equatorial region of the Pacific Ocean is operating on its typical two-to-seven-year cycle. During normal conditions, west-blowing trade winds push warm sea surface temperatures from South America toward Asia. However, those winds break down or reverse direction, allowing warm water to pool near South America. As of Sept. 14, a very strong El Niño was observed in the El Niño 3.4 region in the eastern equatorial Pacific, where average sea surface temperatures sat 2 C warmer than normal.
Did you know? The last El Niño classified as very strong occurred during the 2015-16 winter, while the Prairies experienced a moderate El Niño during the 2023-24 season. Both of those prior periods brought warmer-than-normal temperatures to the region.
Winter Weather Outlook and Temperature Projections for the Prairies
Experts predict the current El Niño will peak during the late fall and winter months. Research scientist Bill Merryfield with Environment and Climate Change Canada states that the odds are tilted toward a relatively mild winter, possibly by a large margin. Temperature differences from normal during past very strong El Niños have reached 5 or 6 degrees averaged over the winter, according to Merryfield. Both Long and Merryfield note that these events typically lead to less snowfall in the Rocky Mountains and warmer temperatures that could reduce snow accumulation across the Prairies, though precipitation trends remain less certain than temperature forecasts.
Historical Soil Data and Precipitation Research
Because precipitation trends are harder to predict during an ENSO cycle, researchers are diving deeper into historical data. David Sauchyn, director of the Prairie Adaptation Research Collaborative at the University of Regina, explains that a proxy of soil data across the Prairies has been collected to track years when soil and trees received varying levels of moisture. This research aims to determine whether drier or wetter periods correlate with El Niño or La Niña events over a 1,000-year proxy record of soil moisture.
Risks of Spring Drought, Wildfires, and Mid-Winter Cold Snaps
Current projections from the CPC show the El Niño continuing into next spring, with a 55 percent chance of a return to neutral conditions in the April-May-June timeframe. Merryfield expresses concern that a reduced snowpack could create problems with streamflow, drought, and wildfires next spring if vegetation is drier than usual and lacks sufficient rainfall to offset the deficit. At the same time, Long emphasizes that a warmer winter does not eliminate the possibility of classic Prairie weather extremes. Big snow events, blizzards, and severe cold snaps can still occur regardless of the overarching seasonal trend.
Frequently Asked Questions
When is the current El Niño expected to peak?
Experts predict the current El Niño will reach its peak during the late fall and winter months.
How does El Niño affect winter temperatures on the Prairies?
According to Environment and Climate Change Canada research scientist Bill Merryfield, historical data shows strong El Niños can bring winter temperatures averaging 5 to 6 degrees above normal.
Does El Niño mean there will be no snow or cold snaps?
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