The winter of 2025-2026 was historically warm across the West with low snowpack, while the East experienced a colder and more active winter.

Now it's time to shift gears and take a look at what the summer of 2026 may hold for North America. 

Weak La Niña to Strong El Niño Transition

During the winter of 2025-2026, weak La Nina conditions were present in the Eastern & Central Equatorial Pacific Ocean, which eventually faded to neutral conditions by late in the season. Heading into the summer of 2026, confidence is high that El Niño conditions will develop, with a strong El Niño phase expected.

What is El Niño?

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 eastern equatorial Pacific.

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

El Niño Criteria

1) The average sea surface temperatures in the Niño-3.4 region of the equatorial Pacific Ocean were at least 0.5°C (0.9°F) warmer than average in the preceding month.

2) The average anomaly of at least +0.5°C (+0.9°F) has persisted or is expected to persist for five consecutive, overlapping 3-month periods.

The images above (courtesy of NOAA) show ocean water temperature compared to average in the Pacific Ocean. The top image is La Niña, showing cooler-than-average ocean water temperatures. The bottom image is El Niño, showing warmer-than-average ocean water temperatures.

ENSO Forecast for Summer 2026

Ocean temperatures in the Pacific Ocean have been undergoing a rapid transition in recent months. Notably, significant warming has occurred in the Eastern Equatorial Pacific, and as of April 2026, ocean temperature anomalies are already well above average off the coast of Ecuador. 

This is a clear signal of an emerging El Niño event, and confidence has been growing in recent months that a strong to very strong El Niño will emerge, starting in the summer months of 2026. 

NOAA's latest ENSO forecast has an 80% chance of El Niño conditions developing this summer, which indicates high confidence.

Image: NOAA Forecast showing the probability of an El Niño, La Niña, and Neutral phase for each three-month period between the spring of 2026 and the early winter of 2026-2027. Blue bars show the percent chance of La Niña, red bars show the percent chance of El Niño, and gray bars show the percent chance of Neutral. The “JJA” label is for “June-July-August”.

Bottom Line – We are already seeing the beginnings of an El Niño-like pattern in late April 2026, and confidence is high that El Niño conditions will be present this summer, eventually strengthening into a "strong" El Niño phase. A strong El Niño occurs when sea surface temperature anomalies in the Niño 3.4 region (Central Equatorial Pacific) are at least +1.5ºC.

An Easterly Based El Niño to Start

The warmest ocean temperature anomalies with this emerging El Niño are occurring in the Eastern Equatorial Pacific Ocean, just off the coast of South America. This indicates the Niño 1+2 region, and is indicative of an easterly-based El Niño.

As the summer progresses, ocean temperature anomalies are projected to rise to well above average levels throughout the Central and Eastern Equatorial Pacific Ocean.

But when the anomalies are highest in the easternmost portions of the Pacific, this tends to have an even greater influence on moisture transport and weather impacts in the U.S. during the summer months. 

Taking a look at the European Seasonal Model for June-July-August, we can see a strong El Niño signature throughout the central and eastern equatorial Pacific, but with the highest ocean temperature anomalies remaining focused in the easternmost region near the South American coast.

Next, let's take a look at some of the big picture signals to look for during an emerging strong summer El Niño, and especially an easterly-based El Niño.

An Active Subtropical Jet Stream

During strong El Niño phases, the subtropical jet stream (typically located in the vicinity of the U.S./Mexico border) tends to be much stronger and more active than usual, which in turn influences weather patterns across the U.S.

The image below shows upper atmosphere wind speed anomalies from May to September during past El Niño summers. The top analog years with the most similar conditions to this year were weighted twice as much as the weaker analog years in this reanalysis image.

The yellow/red colors indicate stronger upper-level winds compared to average, and blue colors indicate weaker upper-level winds compared to average.

More Progressive Upper Level Pattern Favored for Much of the U.S.

During a typical summer season, the upper-level weather pattern tends to become more stagnant over time, especially in July and August, with fewer and weaker weather systems and redundant weather patterns for many areas (hot temperatures, plus thermally and/or orographically-driven thunderstorms).

However, strong El Niños tend to shake up the atmosphere a bit, even in mid-summer, with more frequent troughs and upper atmospheric disturbances. 

In examining past analog years similar to this one featuring emerging summer El Niños, we tend to see trough-dominant signals over the West Coast and Southwest U.S., as well as the Eastern U.S.

While further north, summer El Niños tend to favor ridge-dominant signals over the Pacific Northwest and Western/Central Canada.

Less Active Atlantic Hurricane Season

There is a strong correlation between El Niño and less active Atlantic hurricane seasons. This is because El Niño favors stronger vertical wind shear (change in wind speed/direction with height) in the Atlantic, which can cause developing tropical storms to rip apart, and thus acts as a suppressant. 

The last time we had a summer El Niño in 2023, the hurricane season was fairly active due to abnormally warm ocean temperatures throughout the Atlantic Basin. However, Atlantic Ocean temperatures are much cooler this year, so a less active hurricane season is expected as a result.

More Active Pacific Hurricane Season

El Niño has the opposite effect in the Eastern Pacific Basin. Vertical wind shear tends to be weaker here during summer El Niños, allowing tropical systems to become better organized. As a result, there is a strong correlation between El Niño and active Eastern Pacific hurricane seasons.

This will be something to watch this summer, as tropical storms and hurricanes in the Eastern Pacific can transport abundant moisture into the Western and Southwest U.S., leading to heavy rainfall.

Mixed Signals on El Niño and Monsoon Season

The influence of El Niño on the North American Monsoon is mixed, as there are factors that can be favorable or unfavorable for a monsoon pattern depending on the year and other small-scale factors.

During a traditional monsoonal flow in July and August, the circulation of subtropical moisture around an upper-level high-pressure ridge tends to focus over New Mexico, Arizona, Southern Utah, and Southwest Colorado, with occasional deviations into other regions.

However, El Niño tends to disrupt the subtropical high-pressure ridge over the Southwest U.S. and thus the overall monsoonal regime. 

When examining past monsoon seasons during El Niño summers, there is a fairly strong signal toward larger-scale south to southwest winds aloft associated with West Coast troughs, which tend to favor more substantial moisture transport northward into Utah, Wyoming, Nevada, and Eastern Idaho compared to a typical summer (i.e. areas labeled with the orange arrows in the above map).

Monsoon season rainfall in the more traditional regions of the Southwest U.S. can sometimes be less consistent than usual. But on the other hand, moisture from tropical activity in the Eastern Pacific can enhance the monsoon from time to time.

When examining past summer El Niños, we have found a strong signal toward above-average summer rainfall across the Central Rockies and Great Basin, while Arizona, New Mexico, and Southwest Colorado are less certain, with some analog years featuring above-average summer rainfall, and others below-average summer rainfall.

Tornado Season During El Niño Years

Late spring (May to June) is the prime severe weather and tornado season across the Great Plains and Midwest. 

During the 8 summer El Niño analog years examined, 6 of the 8 years had below-average national tornado counts during May-June combined.

To be fair, observations have significantly increased since 1990 due to more spotters and better reporting compared to prior decades.

Looking only at the 6 analog years since 1990, 4 of the 6 years featured a below-average May-June tornado count, indicating that El Niño tends to favor a somewhat quieter peak season for tornadoes and severe weather. 

However, there are a couple of nuances to point out. 

If we look at May and June individually, in the 8 analog years examined, 5 of the 8 years featured below-average tornado counts in May, but only 4 of the 8 years featured below-average tornado counts in June, meaning that June has roughly equal odds of being more active than usual.

Also, there are some indications that the high plains region extending toward the base of the Rockies could be a bit more active than usual for severe weather and tornadoes during El Niño summers, and June is usually the peak season in this region compared to May in the central and southern plains. 

Other Factors to Consider for this Summer

In addition to the emerging strong eastern-based El Niño this summer, there are a few other climate signals to consider this season...

Gulf of California Ocean Temperatures

Currently, ocean temperatures in the Gulf of California and in the Eastern Pacific Ocean off the coast of Mexico are well above average, which could have a major influence on Western U.S. weather in mid to late summer if these anomalies hold. 

With the emerging eastern-based El Niño in the Equatorial Pacific, these warm Gulf of California waters are likely to be reinforced as cooling trends in this region are unlikely (historically speaking) as El Niño strengthens. The European Season Model also favors these warm anomalies to prevail through the summer.

The warm ocean temperature anomalies in the Eastern Pacific also support the potential for an active Eastern Pacific hurricane season, as warmer waters support more frequent and stronger tropical systems.

Also, above-average Gulf of California temperatures have been linked to stronger monsoon moisture surges. And with this signal already showing up, that could potentially help to boost the monsoon this year.

Gulf of Mexico Ocean Temperatures

Ocean temperatures are currently above average in the Gulf of Mexico and are forecast to stay that way through the summer, although the warm anomalies are lower here compared to the Eastern Pacific and Gulf of California. 

Warm waters in the Gulf of Mexico have long been linked to active weather in portions of the Central and Eastern U.S., as southerly flow from the Gulf supports higher humidity air that can fuel stronger storms and heavy precipitation events.

However, the signals are mixed when combined with strong El Niño summers.

More frequent troughing in the Eastern U.S. during El Niño summers and associated northerly and westerly flows tend to keep Gulf moisture suppressed further south, which can lead to drier air across portions of the Southeast and Mid-Atlantic compared to typical summers.

On the other hand, upper-level troughing and disturbances moving across the Southwest U.S. tend to have a low-level response, in which low-level winds transport moisture from the Gulf of Mexico into the high plains and toward the Front Range and eastern ranges of the Rockies.

The combination of these favored large-scale weather patterns during El Niño, combined with warm Gulf of Mexico ocean temperatures, tends to favor increased rainfall and thunderstorm potential across the Front Ranges of Colorado, Wyoming, and Montana.

Southern and Central Rockies Snowpack

Past studies have found a link between Central and Southern Rockies snowpack and the timing of the onset of monsoon season in the Western U.S.

All other factors equal, if snowpack is well above average across the Southern and Central Rockies, this tends to favor a delayed start to monsoon season because more of the sun's energy in the spring is used to melt the snowpack and less energy is used to heat up the land.

This, in turn, delays the development of the early summer subtropical high pressure ridge over the Southwest U.S., which allows the circulation of monsoon moisture to reach the Southwest U.S. from Mexico.

However, a well below average snowpack across this region has the opposite effect. With less snow cover to melt, the sun's energy can heat up the land surfaces more quickly late in the spring, allowing the subtropical high to develop earlier, with the monsoon often starting earlier.

Snowpack is historically low across the Southern and Central Rockies this spring, which favors an earlier start to monsoon season.

While snowpack can play a role in the onset of monsoon season, there does not appear to be a connection between snowpack and the overall strength of the monsoon. In other words, an early start to monsoon season does not necessarily portend a strong monsoon, all other factors equal.

Analog Years for Summer 2026

We have identified 8 analog years (since 1980) that match up best to what we are expecting this summer. All of these analogs featured either an emerging strong El Niño, or a definitely eastern-based summer El Niño signature.

Of these 8 analog years, 3 analog years were strong matches while 5 were weaker, but still relevant, matches.

Here are the three analog years that are the strongest match for this summer:

• 2015
• 1997
• 2023

Here are the additional analog years that are weaker, but still relevant, matches for this summer:

• 2014
• 2009
• 1991
• 1987
• 1982

Summer 2026 Temperature Outlook

Based on the above factors and analog years evaluated, in the West, we are expected above average summer temperatures from Northern California to the Pacific Northwest to the Northern Rockies, as well as over the Far Southwest into Texas.

From Southern California into the Four Corners and Central Rockies, there are equal chances for above or below average summer temperatures in strong and/or east-based El Niños, and in general, heatwaves tend to be fewer and less intense here compared to non-El Niño summers.

However, there is a signal toward above-average September temperatures in these areas, in contrast to the preceding spring and mid-summer.

In the East, there is a signal toward above-average temperatures along the Gulf Coast and Florida during strong and/or east-based El Niño summers.

However, there is a signal toward below-average summer temperatures across the Lower Great Lakes region, with equal chances for above or below average summer temperatures across the Mid-Atlantic and Northeast. Summer heat waves also tend to be fewer and less intense in El Niño summers compared to other summers.

Summer 2026 Rainfall Outlook

Based on the above factors and analog years evaluated, in the West, we are expecting above-average late spring and summer rainfall across the Sierra, Great Basin, Central Rockies, Front Range, and High Plains, with equal chances of above or below normal rainfall across Arizona, New Mexico, and Southwest Colorado.

As previously mentioned, emerging strong and east-based El Niño summers have a clear signal toward above-average rainfall in these green-shaded areas across the West. The connection is less clear across the core monsoon region of the Southwest and across the Northern Rockies.

El Niño summers tend to favor below-average rainfall across the Cascades and British Columbia Coast Range, while signals are less clear across the BC Interior and Canadian Rockies.

In the East, there is a strong signal toward below-average rainfall across the Southeast and Southern Mid-Atlantic during strong and/or east-based El Niño summers, which isn't the best news, given the ongoing drought across this region. However, the Florida Peninsula is favored for above-average summer rainfall during El Niño summers.

In the Northeast, strong and/or east-based El Niño summers tend to favor above-average rainfall across New York, New England, and Southern Quebec.

Across the Midwest, there is no clear signal toward above or below average rainfall.

Moisture and Humidity

We also examined precipitable water anomalies during these analog years, which is a measure of the amount of water vapor in the atmosphere. This is a good proxy for atmospheric moisture available for thunderstorms and rainfall, as well as comfort levels (i.e. humidity).

We found that moisture levels tend to be above average across much of the West, which makes sense given the above-average rainfall signal we see for much of this region.

Interestingly, there is a signal toward below-average moisture across much of the East, except in Florida. This is likely a result of the troughing signal and more suppressed Gulf of Mexico moisture that is typical of summer El Niños.

As a result, summer humidity levels (in terms of "real feel"), may not be as bad as normal across the East during the summer, relatively speaking anyways. 

Summer Wildfire Thoughts

Summer fire season in the West is more challenging to forecast than you might think, as it is dependent on a lot more than just winter snowpack. In fact, short-term weather conditions arguably play just as big, if not a bigger, role in fire risk than preceding winter snowpack and drought conditions, though both are important.

Extended hot and dry spells with dry thunderstorms and/or windy conditions in the summer can lead to a bad fire season even after a good winter, whereas frequent showers and thunderstorms in the spring and summer, fewer heatwaves, and/or limited dry thunderstorm and high wind events can overcome a poor winter to result in a milder fire season.

Here is what we are looking for in terms of overall wildfire risk by region in the West right now, though keep in mind this can change as the summer progresses depending on short-term weather events.

Also, this is based on preceding weather/climate conditions and our seasonal summer forecast, and doesn't account for localized knowledge on vegetation fuel conditions, so we also recommend following your regional fire center. 

Higher Concern for Summer Wildfires:

• Pacific Northwest (Especially Oregon) – Low snowpack, hotter and drier than average summer expected, similar setup to 2015, which was a bad fire season in the PNW.

Conditional Concern for Summer Wildfires:

• California – Below average snowpack, OK from a drought perspective, above average temperatures favored Northern California, more summer precipitation than average favored in El Niño in the mountains, but there could also be some dry thunderstorm concerns.
  
  
• West/Southwest Colorado – Historically low snowpack, early summer pre-monsoon fire risk looks greater, heatwaves less common in El Niño, will largely hinge on late spring rainfall and whether or not the monsoon season delivers.
  
  
• Arizona & New Mexico – Similar outlook to West/Southwest Colorado
  
  
• Montana & Idaho – Low snowpack and drought concerns, wetter signal for Eastern Idaho/Southern Montana may help, Northern Idaho/Montana likely at a greater risk for fires with above average temps favored and no clear summer rainfall signal.
• BC Interior & Canadian Rockies – Deep snowpack at higher elevations could delay fire season, but hotter summer temps favored in El Niño could eventually increase the fire risk, higher risk closer to U.S. border, where snowpack wasn't as deep.

Somewhat Lower (but Not Zero) Concern for Summer Wildfires:

• Colorado Front Range – Historically low snowpack, but strong correlation toward wet spring/summer in similar El Niño years should help to curb the fire risk, severe heatwaves are also less common during El Niño.
  
  
• Utah – Similar to the Front Range, historically low snowpack, but El Niño favors more abundant spring and summer rainfall compared to average, which should help to curb fire danger.
  
  
• Wyoming – Below-average snowpack and drought conditions, but a strong signal toward above-average late spring and summer rainfall during El Niño should help to curb fire danger.

Keep in mind that even in these "lower concern" areas, if the summer precipitation forecast does not pan out for any of these areas, or if there are any shorter-term hot and dry spells, that could change the situation completely, given the low snowpack and ongoing drought concerns in these areas.

The Seasonal Forecast Caveat

Keep in mind that every summer is unique, and there will always be factors we cannot anticipate months or even weeks in advance.

Also, from a planning perspective, be aware that heat waves, wildfires, thunderstorms, lightning danger in high mountain terrain (and anywhere outdoors), severe weather, and heavy rain/flash flooding can always occur under the right patterns in any given summer.

We have you covered with OpenSnow this summer, whether it's minimizing lightning danger in the mountains, planning around expected rain, avoiding smoke from wildfires, or managing severe weather risk.

Alan Smith, OpenSnow Meteorologist

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