The 2022-2023 winter was about average in terms of snowfall for Washington. The season started out strong, with above average snowfall for November and December. January and February were a bit underwhelming, but spring storms brought consistent snow in March and April resulting in an impressive spring snowpack.

As we look ahead to the 2023-2024 winter season, it's important to remember that any winter outlook will contain an inherent degree of uncertainty. However, there are a few clues that we can keep an eye on.

Following three straight winters of La Niña, we are now heading into a potentially strong El Niño this season. 

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.

In general, El Niño winters tend to favor below normal snowfall in Washington. There is also some indication that a stronger El Niño favors even less snowfall than weak and moderate events.

Overall, it is more likely that early season (Nov-Dec) snowfall will be normal to above normal, while mid to late season (Jan-Apr) is more likely to be normal to below normal. It is also interesting to note that the farther south you go, the less below normal the mid to late season period tends to be.

Historical El Niño Seasons @ Mt. Baker

After looking back at the four most recent significant El Niño years and comparing them against the 30-year median snow water equivalent (SWE) on March 31 of 34.5 inches at the Wells Creek SNOTEL near Mt Baker, I've found that the median SWE on March 31 during those El Niño years is 28.2 inches or 82% compared to the 30-year normal.

SWE on March 31 During Significant El Niño Years

• 1991-2020: 34.5" (30-year normal)
• 1997-1998: 27.7"
• 2002-2003: 24.0"
• 2009-2010: 27.2"
• 2015-2016: 34"

For timing, when looking at the change in SWE each month during the five most recent significant El Niño episodes and comparing them against the 30-year median change in SWE for that month...

• November: 4" (96%)
• December: 13.8" (113%)
• January: 16.2" (87%)
• February: 21.8" (79%)
• March: 28.3" (81%)
• April: 22.9" (78%)

It tends to be that the early season (Nov-Dec) is more likely to be normal to above normal, while mid to late season (Jan-Apr) is more likely to be normal to below normal. 

Historical El Niño Seasons @ Stevens Pass

After looking back at the seven most recent significant El Niño years and comparing them against the 30-year median snow water equivalent (SWE) on March 31 of 35.9 inches at the Stevens Pass SNOTEL, I've found that the median SWE during those El Niño years is 31.1 inches on March 31 or 87% compared to the 30-year normal.

SWE on March 31 During El Niño

• 1991-2020: 35.9" (30-year normal)
• 1982-1983: 23.8”
• 1986-1987: 43.6"
• 1991-1992: 23.7"
• 1997-1998: 36.1"
• 2002-2003: 31.3"
• 2009-2010: 27.5"
• 2015-2016: 31.6"

Two out of the seven El Niño years produced above normal snow water equivalent (SWE) while five out of the seven were below at Stevens Pass on March 31.

For timing, when looking at the change in SWE each month during the seven most recent significant El Niño episodes and comparing them against the 30-year median change in SWE for that month...

• November: 6" (120%)
• December: 17" (113%)
• January: 24" (87%)
• February: 28.7" (89%)
• March: 30.7" (84%)
• April: 19.7" (64%)

It tends to be that the early season (Nov-Dec) is more likely to be above normal, while mid to late season (Jan-Apr) is more likely to be below normal. 

Historical El Niño Seasons @ Snoqualmie Pass

After looking back at the seven most recent significant El Niño years and comparing them against the 30-year median snow water equivalent (SWE) on March 31 of 51.3 inches at the Olallie Meadows SNOTEL near Snoqualmie Pass, I've found that the median SWE during those El Niño years is 45.9 inches on March 31 or 89% compared to the 30-year normal.

SWE on March 31 During El Niño

• 1991-2020: 51.3" (30-year normal)
• 1982-1983: 49.6”
• 1986-1987: 47.9"
• 1991-1992: 26.7"
• 1997-1998: 55.5"
• 2002-2003: 42.1"
• 2009-2010: 43.9"
• 2015-2016: 55.3"

Two out of the seven El Niño years produced above normal snow water equivalent (SWE) wth five out of the seven were below near Snoqualmie Pass on March 31.

For timing, when looking at the change in SWE each month during the seven most recent significant El Niño episodes and comparing them against the 30-year median change in SWE for that month...

• November: 7" (120%)
• December: 21.2" (109%)
• January: 31.4" (100%)
• February: 38.3" (93%)
• March: 45.8" (88%)
• April: 40.7" (80%)

It tends to be that the early season (Nov-Dec) is more likely to be above normal, while mid to late season (Jan-Apr) is more likely to be normal to slightly below normal. 

Historical El Niño Seasons @ Crystal Mountain

After looking back at the seven most recent significant El Niño years and comparing them against the 30-year median snow water equivalent (SWE) on March 31 of 34.1 inches at the Corral Pass SNOTEL near Crystal Mountain, I've found that the median SWE during those El Niño years is 30.1 inches on March 31 or 88% compared to the 30-year normal.

SWE on March 31 During El Niño

• 1991-2020: 34.1" (30-year normal)
• 1982-1983: 27.1”
• 1986-1987: 33.4"
• 1991-1992: 26.9"
• 1997-1998: 32.5"
• 2002-2003: 31.3"
• 2009-2010: 24.2"
• 2015-2016: 35.5"

One out of the seven El Niño years produced above normal snow water equivalent (SWE) while six out of the seven were below near Crystal Mountain on March 31.

For timing, when looking at the change in SWE each month during the seven most recent significant El Niño episodes and comparing them against the 30-year median change in SWE for that month...

• November: 6.9" (101%)
• December: 17.2" (118%)
• January: 21.6" (95%)
• February: 26" (92%)
• March: 31.2" (89%)
• April: 30.4" (82%)

It tends to be that the early season (Nov-Dec) is more likely to be above normal, while mid to late season (Jan-Apr) is more likely to be slightly below to below normal. 

Historical El Niño Seasons @ White Pass

After looking back at the seven most recent significant El Niño years and comparing them against the 30-year median snow water equivalent (SWE) on March 31 of 21.6 inches at the White Pass SNOTEL, I've found that the median SWE during those El Niño years is 19.8 inches on March 31 or 92% compared to the 30-year normal.

SWE on March 31 During El Niño

• 1991-2020: 21.6" (30-year normal)
• 1982-1983: 27.9”
• 1986-1987: 17.3"
• 1991-1992: 11"
• 1997-1998: 21.5"
• 2002-2003: 17.7"
• 2009-2010: 16"
• 2015-2016: 27.4"

Two out of the seven El Niño years produced above normal snow water equivalent (SWE) while five out of the seven were below at White Pass on March 31.

For timing, when looking at the change in SWE each month during the seven most recent significant El Niño episodes and comparing them against the 30-year median change in SWE for that month...

• November: 3.4" (117%)
• December: 12.1" (131%)
• January: 14.7" (102%)
• February: 17.6" (91%)
• March: 20.1" (93%)
• April: 15.6" (87%)

It tends to be that the early season (Nov-Dec) is more likely to be above normal, while mid to late season (Jan-Apr) is more likely to be normal to slightly below normal. 

Historical El Niño Seasons @ Mt. Spokane

After looking back at the five most recent significant El Niño years and comparing them against the 30-year median snow water equivalent (SWE) on March 31 of 19.3 inches at the Quartz Peak SNOTEL near Mt. Spokane, I've found that the median SWE during those El Niño years is 16.6 inches on March 31 or 86% compared to the 30-year normal.

SWE on March 31 During El Niño

• 1991-2020: 19.3" (30-year normal)
• 1991-1992: 10.5"
• 1997-1998: 19.8"
• 2002-2003: 14.1"
• 2009-2010: 15.4"
• 2015-2016: 23.1"

Two out of the five El Niño years produced above normal snow water equivalent (SWE) while three out of the five were below near Mt. Spokane on March 31.

For timing, when looking at the change in SWE each month during the seven most recent significant El Niño episodes and comparing them against the 30-year median change in SWE for that month...

• November: 4.2" (130%)
• December: 11.5" (133%)
• January: 13.6" (94%)
• February: 16.3" (86%)
• March: 16.3" (85%)
• April: 5" (49%)

It tends to be that the early season (Nov-Dec) is more likely to be above normal, while mid to late season (Jan-Apr) is more likely to be normal to slightly below normal. 

Historical El Niño Seasons @ Hurricane Ridge

After looking back at the three most recent significant El Niño years and comparing them against the 30-year median snow water equivalent (SWE) on March 31 of 41.6 inches at the Waterhole SNOTEL near Hurricane Ridge, I've found that the median SWE during those El Niño years is 40.3 inches on March 31 or 97% compared to the 30-year normal.

SWE on March 31 During El Niño

1991-2020: 41.6" (30-year normal)
2002-2003: 35"
2009-2010: 42"
2015-2016: 44"

Two out of the three El Niño years produced above normal snow water equivalent (SWE) with the other year coming in below near Hurricane Ridge on March 31.

For timing, when looking at the change in SWE each month during the seven most recent significant El Niño episodes and comparing them against the 30-year median change in SWE for that month...

• November: 2.2" (40%)
• December: 12.3" (74%)
• January: 25" (93%)
• February: 29.9" (87%)
• March: 40.2" (96%)
• April: 40.8" (96%)

Here, in the Olympic Mountains, the seasonal trends are reversed. The early season (Nov-Dec) is more likely to be below normal, while mid to late season (Jan-Apr) is more likely to be normal to slightly below normal. 

Temperatures During Significant El Niño Winters

While snowfall is our primary focus during ski season, temperatures are also a factor in terms of snow totals and snow quality. It is especially important in Washington where snow levels can be a significant factor in the winter season. 

I examined NOAA’s National Center for Environmental Information (NECI) Climate Division dataset, which takes in station observations throughout the United States. A quick look at the NOAA/NECI map below for the El Niño winters analyzed above shows above normal temperatures for all of Washington, especially in the eastern part of the state.

 
The precipitation anomaly during these years lines up fairly well with the snotel data shared earlier, with below normal results for all of the Cascades.

2015-2016 El Niño Season

The most recent El Niño in 2015-16 produced normal to above normal snowfall across most of Washington. The map below shows the March 31, 2016 basin average snow water equivalent (SWE) anomaly. 

This map uses SNOTEL and other station data to create a hydrologic basin-wide average. 

Overall, history tells us that Washington tends to be below average for snowfall during El Niño winters, with the potential for a stronger start and weaker end to the season. Southwestern Washington tends to do better because of the influence of atmospheric rivers during El Niño winters. 

An additional factor in the El Niño winters analyzed above is that they can be variable. While the average is near normal, several seasons were on the extreme ends of low to high snow seasons. While the statistics above are using the seven past El Niño winters, every winter can be different and will have its own unique impacts.  

There are a few additional caveats to this year’s El Niño. First, the atmospheric response to the above normal tropical Pacific ocean waters has been much slower than previous El Niño years. Secondly, the sea-surface temperatures across the entire globe are well above normal, resulting in less of a contrast between these areas. In total, these two factors could lead to more unexpected temperature and precipitation patterns throughout the winter. 

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.

But don't just take my word for it ... "Any weather app can give a mediocre forecast for a mountain town, but only OpenSnow provides a good idea of actual mountain conditions. It's a small price to pay ($29.99/year) for the best weather forecasts." – Real App Review

Luke Stone
Forecaster, OpenSnow