The 2022-2023 winter in Idaho was a memorable ski season that kept on giving and giving from start to finish. We got an early start with snowfall in late October, most Idaho ski areas opened on Thanksgiving weekend, and it snowed hard and stayed cold in the mountains all season. The impact was felt statewide. 

As we look ahead to the 2023-2024 winter season, we are transitioning from three years of La Nina in a row to El Nino, with a rise in ocean temperatures.

In general, El Nino is expected to bring slightly warmer winter-time temperatures. Depending on how the storm tracks play out, it could bring below-average snow, average snowfall, or above-average snowfall. History shows that El Nino can be good for Idaho or not so great, depending on how the storm tracks play out. 

However, there are a few clues that we can keep an eye on thanks to everyone's favorite weather phenomenon: El Niño. Sea surface temperatures are showing a strengthening El Niño event.

El Niño, Explained

The term El Niño refers to the large-scale ocean-atmosphere climate phenomenon linked to periodic warming in sea-surface temperatures across the central and east-central equatorial Pacific.

El Niño represents the warm phase of the ENSO cycle and means that the ocean water temperatures are warmer than average.

Ski Season Snowfall vs. El Niño

The map below shows winter snowfall during seven significant El Niño episodes across the United States. The higher the number, the stronger the El Niño. The blue dots are above average, the white dots are average, and the orange dots are below average snowfall.

Looking back at seven strong El Nino winters from the 1982-83 ski season to the 2015-16 ski season, we see that the results at Idaho ski areas were decidedly mixed.

The 1982-83 ski season, for instance, was an absolute HUMDINGER, as my hockey coach used to say. Bogus Basin got the most snowfall in its long history, 493 inches that year. The record still stands! Statewide, all of Idaho’s ski areas had a strong year in 1982-83. Heavy snowfall and a long ski season.

In other years, El Nino brought warmer temperatures and less snow, with long periods of high pressure camped off the Pacific Coast that steered the storms north to British Columbia or to the south of Idaho. I remember the 1986-87 and 1991-92 El Nino years having that type of experience.

We got enough snow for the ski areas to operate, but you had to dance around the rocks or other hazards. In the backcountry, the snowpack turned into a weird, sugary bottomless pile of goo that often wasn’t skiable, regardless of aspect. Not universal, but you get the idea.

Let’s take a look at the historical record of select El Nino winters at six of Idaho’s ski areas across the state to see what we can learn.

Historical El Nino Seasons @ Bogus Basin Mountain Recreation Area

Looking back at the seven most recent strong El Nino winters at Bogus Basin, and comparing them to the 30-year median Snow Water Equivalent (SWE) on March 31 at the Bogus Basin SNOTEl site (elevation 6,340 feet) of 24.3 inches, I’ve found that the median SWE during those El Nino years was 23 inches on March 31, or 95 percent compared to the 30-year normal.

SWE on March 31 During El Niño

• 30-year average: 24.3”
• 1982-83: 48.9”
• 2015-16: 26.0”
• 1997-98: 24.4”
• 2009-10: 23.2”
• 2002-03: 21.8”
• 2002-03: 21.8”
• 1986-87: 16.8”
• 1991-92: 16.5”

When you look back at the total snowfall at Bogus Basin during those El Nino years, in 1987 and 1992, Bogus logged only about 125 inches of snow, among the lowest years ever recorded in the last 40 years. Bogus limped along in those years with 50-70 percent of normal snowfall, and then in April, the ski season petered out with hardly any snow at all and warmer temps.

In the El Nino years 1998, 2003, and 2010, however, Bogus finished the season strong with 125 to 150 percent of normal snowfall in April. The 2015-2016 season was a decent one at Bogus, with SWE exceeding the 30-year average by March 31, and then it kind of petered out in April with not much snow (66% of normal) and warmer temps.

Conclusion: Mixed bag. One huge year; four average years; and two weak years.

Thanks to Susan Saad for the Bogus Basin notes.

Historical El Nino Seasons @ Brundage Mountain Resort

Brundage Mountain is about 100 miles north of Bogus Basin, but the storm patterns can be different, and the temperatures at Brundage in McCall tend to swing a bit cooler than Bogus. Overall, strong El Ninos tend to bring more snow to Brundage than weak El Ninos, according to SNOTEL data and ski area records.

Looking back at the seven most recent strong El Nino winters at Brundage, and comparing them to the 30-year median Snow Water Equivalent (SWE) on March 31 at the Brundage Reservoir SNOTEL site (elevation 6,250 feet) of 30 inches, I’ve found that the median SWE during those El Nino years was 33.2 inches on March 31, or 111 percent compared to the 30-year normal.

SWE on March 31 During El Niño

• 30-year average: 30.0”
• 1982-83: 47.5”
• 1986-87: 52.0”
• 2002-03: 35.2”
• 2015-16: 34.0”
• 1997-98: 24.7”
• 2009-10: 21.6”
• 1991-92: 17.6”

So overall, it appears that strong El Nino winters can be a positive thing at Brundage Mountain. It’s interesting to see that the weak winter of 1986-87 at most Idaho ski areas turned out to be a great season at Brundage. They opened on Nov. 27 and closed on April 12. The snowpack numbers at Brundage that year were not impressive – hovering in the 50-65 percent range for most of the winter months – but November was slightly above normal at 108 percent, starting off the season with a bang and allowing them to open on Thanksgiving weekend.

Other El Nino years that went well for Brundage:

1997-98: A very strong El Nino brought Brundage a solid winter. They opened on Nov. 26 on Thanksgiving weekend and closed in mid-April, as per usual. They logged 390 inches of snowfall that year, exceeding their average of 350 inches a year.

2002-03: This was a 300-inch season, not that far from average. The snow came late, and Brundage opened on Dec. 18, later than normal. But the storms picked up and remained above 100 percent of normal, December-April, month by month, as the season progressed.

2009-10: The snow came late, once again. Opening day was Dec. 18, but the snow coverage was adequate throughout the season, ranging from 68-82 percent of normal, month by month. By the tail end of the season, they had measured 245 inches of snowfall at the base area and remained open for bonus weekends into May. This was an example of a season where the storms were frequent enough and cold enough to build the base, and their Northwest-facing slopes preserved snow quality between storms.

2015-16: This was more of an average year. Opening day was Dec. 5 and closing day was April 24. Snowfall was measured at 302 inches at the base area, the third-highest total in the last 10 years.

Thanks to April Whitney for the Brundage notes. 

Historical El Nino Seasons @ Sun Valley  

Sun Valley is located in the middle of South-Central Idaho, but it tends to have its own unique weather patterns being located in the Big Wood River Valley, which has a north-south aspect, framed by the Smoky Mountains and the Pioneer Mountains. Thus, the most potent winter storms that come into the Sun Valley area tend to come up from the south, Nevada, and Utah.

That said, Sun Valley’s snowfall during the strong El Nino winters tends to be similar to how the winters performed elsewhere in Idaho. 1982-83 was a huge winter, 1998 and 2003 were above average, and the more anemic 1987 and 1992 winters were, well, somewhat meek. All of that said, Sun Valley’s investment in a world-class snowmaking system years ago has managed to buffer the impacts of lower snowfall years. Sun Valley has been rated No. 1 in North America for the last two years running by Ski magazine readers.

Looking back at the seven most recent strong El Nino winters at Sun Valley, and comparing them to the 30-year median Snow Water Equivalent (SWE) on March 31 at the Dollarhide SNOTEL site (elevation 8,420) of 23 inches, I’ve found that the median SWE during those El Nino years was 23 inches on March 31, or 100 percent compared to the 30-year normal. But if you look closer, the snowfall patterns were like a yo-yo:

SWE on March 31 During El Niño

• 30-year average: 23”
• 1982-83: 38.7”
• 2015-16: 29.0”
• 2002-03: 23.4”
• 1997-98: 21.6”
• 2009-10: 17.5”
• 1991-92: 16.1”
• 1986-87: 14.7”

Looking at the snowfall numbers month by month in those El Nino years, Sun Valley tended to start out the ski season strong with 200-400 percent of normal snow in October and more than 110-160 percent in November most of the time. 1987 started out weak and remained weak, and 1998 started out slow and finished strong. 1992 started strong, and kind of petered out January-April 2016 started out slow but really made up ground December-March with snowpack readings exceeding 114-130 percent.

Conclusion: Two great years; two average years, three below-average years.

Historical El Nino Seasons @ Schweitzer Mountain Resort

Schweitzer Mountain Resort is located in the northernmost part of Idaho compared to the rest of Idaho’s ski areas, so it sits at a higher latitude, 60 miles from the Canadian border. Comparing snowpack in the strong El Nino years, Schweitzer had a very strong winter in 1982-83 like the rest of Idaho. 1987 at Schweitzer was much better than the rest, 1998 and 2003 were average years. 2016 was an above-average year. 1992 and 1998 started strong but petered out at the end of the season. So it’s a mixed bag as well.

Looking back at the seven strong El Nino winters at Schweitzer, and comparing them to the 30-year median Snow Water Equivalent (SWE) on March 31 at the Schweitzer SNOTEL site (elevation 6,090 feet) of 46.8 inches, I’ve found that the median SWE during those El Nino years was 45 inches on March 31, or 96 percent compared to the 30-year normal. Among all of the Idaho ski resorts, it seems that Schweitzer’s numbers are more consistent across the board:

SWE on March 31 During El Niño

• 30-year average: 46.8”
• 1982-83: 58.5”
• 2015-16: 52”
• 2002-03: 48”
• 1986-87: 46.3”
• 1997-98: 43”
• 2009-10: 34”
• 1991-92: 35.9”

Looking at month-to-month snowfall and SWE percentages compared to the 30-year average, Schweitzer showed more consistency in the strong El Nino winters. They started the season strong in 1982-83, 1986-87, 1991-92 and 1997-98. And then by February, the snowfall numbers dropped in all of those years except the banner year of 1983 and snowfall tapered in March and April into the 60-75 percent range.

In the winter of 2002-2003, Schweitzer started out slow but had a strong December and January, and stayed in the 94-97 percent of normal in February-April for a solid ski season. The winter of 2009-2010 was the weakest of the seven El Nino years analyzed, with snowfall numbers ranging from 68-81 of normal December-April. 2016 started slow but from December-March, Schweitzer received 97-109 percent of average snowfall. They finished the season strong, ranking second of the seven El Nino years with 52” of SWE, 6” above average.

Conclusion: El Nino winters generally brought consistently strong results in five out of the seven years except for 2009-10 and 1991-92.

Historical El Nino Seasons @ Lookout Pass Ski & Recreation Area

Lookout Pass also is located in northern Idaho, along the Interstate 90 corridor, on the Idaho-Montana border. Snow data shows that the seven-strong El Nino winters played out a bit differently at Lookout than at Schweitzer, but there are similarities. 1983 was an off-the-charts big winter like it was everywhere in Idaho. 1986-87, 1991-92 and 1997-98 were all steady and strong. But the 2002-2003, 2009-10, and 2015-16 winters were much weaker in terms of snowfall at Lookout.

Looking back at the seven strong El Nino winters at Lookout, and comparing them to the 30-year median SWE on March 31 at the Lookout SNOTEL site (elevation 5,190 feet) of 25.7 inches, I’ve found that the median SWE during those El Nino years was 23.5 inches on March 31, or 91 percent compared to the 30-year normal.

SWE on March 31 During El Niño

• 30-year average: 25.7”
• 1982-83: 32.4”
• 1986-87: 25.3”
• 1997-98: 25.3”
• 1991-92: 23.4”
• 2015-16: 22”
• 2002-03: 20.6”
• 2009-10: 15.6”

Looking at month-to-month snowfall and SWE percentages compared to the 30-year average, the El Nino Northern Idaho storm track in 1982-83, 1987-88, 1991-92, and 1997-98 was favorable at Lookout, much like it was at Schweitzer. The ski seasons started strong in those years with more than 200 percent of normal snowfall in three of the five years, and in 1991-92, the season started with a bang, and 525 percent of normal snow in October and 219 percent of normal snow in November.

In 2002-2003, October started well with 150 percent of normal snow, but then the snowfall numbers fell into the 50-60 percent range for the rest of the season from November to March, ending with a slightly stronger April with 78 percent of normal. The 2009-2010 season tracked similarly to 2002-2003, and it ended up with the lowest snowpack numbers in March of all seven El Nino winters. The 2015-16 winter fared a little better, with snowfall numbers in the 70-87 percent range.

Conclusion: One big winter, three average winters, and three below-average winters.

Historical El Nino seasons @ Pomerelle Mountain Resort

Pomerelle Mountain Resort is located high in the Albion Mountains with a base area of 7,700 feet and a summit elevation of 8,762 feet. It’s the home ski area for the Magic Valley region of South-Central Idaho, not far from the Nevada border. Snow storms that blow into Idaho from Northern California and Nevada can deliver significant quantities of snow at Pomerelle, sometimes more than a foot of powder at a time.

The tale of the seven-strong El Nino winters at Pomerelle is similar to how the winters played out at Bogus Basin and Sun Valley in terms of the big winter of 1982-83, and the weak winter in 1986-87, but Pomerelle tells its own unique story from there. The winter of 2015-16 was a major one at Pomerelle, with snowfall percentages exceeding 120 percent of normal all season long. The 2002-2003 season was similar to the weak El Nino winter of 1986-87, while the 2009-2010 season started slow and then gathered steam to finish strong.     

Looking back at the seven strong El Nino winters at Pomerelle, and comparing them to the 30-year median SWE on March 31 at the Howell Canyon SNOTEL site (elevation 7,980 feet) of 22 inches, I’ve found that the median SWE during those El Nino years was 18.5 inches on March 31, or 91 percent compared to the 30-year normal.

• 30-year average: 22.0”
  
• 1997-98: 26.8
• 2015-16: 26.4”
• 1982-83: 23.1”
• 2009-2010: 18.1”
• 1991-92: 13.1”
• 2002-2003: 11.4”
• 1986-87: 11.1”

Looking at month-to-month snowfall and SWE percentages compared to the 30-year average, the snowfall numbers tell a similar tale. The 1986-87 winter started out with 97 percent of normal snow in November, and then the ski season went downhill from there with very low snowfall numbers ranging from 40-52 percent of normal the rest of the season. The 1991-92 winter started strong with 232 percent of normal snow in November and 110 percent of normal in December, and then the numbers petered out in the rest of the season, ranging from 48 percent of normal in March to 70 percent of normal in January.

The 2002-2003 season was another weak one with snowfall numbers ranging from 50-79 percent, half of the normal snow by the end of March that year. The 1997-98 season, however, started slowly with meager numbers in November and December, but it picked up steam the rest of the way, ranging from 117 percent of normal in January to 132 percent in April, finishing strong. The 2009-2010 season had a similar trajectory but with snowfall ranging from 82-100 percent from December to April. The 2015-16 winter was strong across the board, with snowfall from December to April landing in the 120-158 percent of normal range.

Conclusion: Three above-average winters and four below-average winters – a mixed bag.

Overall, history tells us that Idaho tends to be right around average for snowfall during El Niño winters. 

Having said all of this, for skiers and snowboarders, keep in mind that when it comes to finding the best conditions, it’s all about timing. To have the best chance of enjoying the deepest powder, our recommendation is to book a trip 7-10 days in advance.

Sometimes, longer-range forecasts can identify possible storms 1-2 weeks (or longer) in advance, but often, forecast confidence in the details of each storm only begins to increase when the system is about one week away or closer.

If you're ready to level up your weather app for the upcoming winter season, consider upgrading to OpenSnow All-Access. Whether you’re chasing powder, searching for sunny days, or something in between, our 10-day snow forecasts, expert "Daily Snow" forecasters, and high-resolution weather maps have you covered.

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Steve Stuebner, Idaho forecaster