Sunscreen instead of ski pants? What El Niño could mean for the upcoming Prairie winter

El Niño is making its return after a nearly eight-year hiatus, and forecasters say it could impact winter weather on the Prairies.

The climate pattern happens when the temperature of Pacific Ocean waters along the equator off the coast of Peru rises above normal.

The air above that water then warms and moves northward.

In Western Canada, this intrusion of warmer air can change the overall pattern of the polar jet stream — a narrow band of fast-moving air that separates colder weather to the north from milder weather to the south.

"El Niño conditions, in general, will give [the Prairies] warmer than average winters and drier than average winters," said Terri Lang, a meteorologist with Environment and Climate Change Canada.

"Those moisture-bearing low pressure systems that travel along the jet will also be … further north."

But snowstorms and frigid temperatures are still possible, even in an El Niño winter, said Lang.

El Niño is the opposite of La Niña, where Pacific Ocean waters in the same region are cooler than normal. This typically brings more moisture and colder than average temperatures to the Prairies.

The National Oceanic and Atmospheric Administration (NOAA) in the U.S. says the last three years have seen La Niña winters.

This El Niño could be stronger

The last El Niño, during the 2015-16 winter, was dubbed one of the stronger systems since data collection began around 1900.

That winter, Pacific Ocean temperatures rose more than 2 C above average in the region of the Pacific called Niño 3.4 — the area most watched to determine El Niño's strength.

That event left the Prairies up to 4 C warmer than normal from December through February. It also left an extreme moisture deficit.

Some climate agencies are predicting another strong El Niño this time around, with NOAA forecasting a 55 per cent chance of such an event.

David DeWitt, director of NOAA's Climate Prediction Center, said Niño 3.4 temperatures are around 1.9 C above average and are expected to intensify through December.

But DeWitt cautions against relying on sea surface temperatures alone as a predictor, since other seasonal weather phenomena across the globe could also impact El Niño's strength.

"You could have a relatively weak El Niño that has relatively strong impacts … or you could have a very strong event that has relatively modest impacts," said DeWitt.

There is speculation that El Niño could increase temperatures even further in 2024 — after 2023 is poised to become the hottest year on record.

As of Nov. 9, NOAA was predicting a 62 per cent chance that El Niño will continue during April through June 2024.

Dry, warm fall continues on the Prairies

Environment Canada's Lang said that could further complicate things for the Prairies, especially after a record-shattering forest fire season and intense drought.

"We had a dry winter last winter, we had a dry spring, we had a dry summer" Lang said.

"The whole summer, most of Western Canada was on fire. We went through a dry fall, so coming into another dry winter could be really, really problematic."

The latest drought data shows most of the Prairies are drier than normal, with parts of southern Alberta experiencing "exceptional" drought.

Data as of Nov. 24 from Environment Canada shows many Prairie cities may already be seeing El Niño's effects.

Calgary usually sees an average daytime high of 3.4 C in November. This month it's been 8.7 C.

Edmonton, Saskatoon, Regina and Winnipeg have also been above their monthly averages so far.

Edmonton International Airport hasn't reported any snow this month — and it could soon be the first snowless November since the airport's weather station opened in 1960.

Saskatoon barely has measurable snow on the ground. The average snow depth at the end of November is usually around four centimetres.

Volunteer reports from around that city via CoCoRaHS (the Community Collaborative Rain, Hail and Snow Network) show only up to 1.8 centimetres fell between Nov. 1 and 24, with the average snowfall in November being 13.4 centimetres.

Regina, meanwhile, has received around 17 centimetres so far in November — more than the monthly average of 13 centimetres. Almost all of that fell in less than two hours on Nov. 7, due to an intense band of snow.