Weather
The climate pattern that has shaped global weather for the past year is nearly done. La Niña is weakening quickly, and by summer, its warm-water counterpart El Niño could take over.
NOAA’s Climate Prediction Center issued a dual ENSO Alert on March 12: a La Niña Advisory and an El Niño Watch simultaneously. A shift to ENSO-neutral conditions is expected within the next month, with neutral likely to hold through May-July 2026. After that, El Niño carries a 62% chance of developing by June-August and is expected to persist through at least the end of 2026.
La Niña continued through February, with the key Niño-3.4 sea surface temperature index sitting at -0.5°C, just barely in La Niña territory. Anything below -0.5°C and we’re in La Niña. Above +0.5°C and it’s El Niño. Right now, we’re nearly back to the middle.
Subsurface ocean temperatures across the Pacific have been rising steadily, a large reservoir of warm water building at depth that could fuel El Niño development later this year. That subsurface heat is one of the main reasons forecasters are taking the El Niño threat seriously.
Atmospheric conditions still reflect La Niña. Trade winds remain stronger than normal over the east-central Pacific, convection is suppressed near the Date Line, and the Southern Oscillation Index is positive. But that atmospheric signal is fading.
How Strong Could El Niño Get? That’s the big question, and right now nobody has a firm answer. There is roughly a one-in-three chance El Niño reaches “strong” status by October-December 2026, defined as a Niño-3.4 temperature anomaly of +1.5°C or higher.
- Bookmark: SnowBrains Snow Forecasts
It’s also worth noting that spring is historically the trickiest time to forecast ENSO. Model forecasts issued during the Northern Hemisphere spring tend to be less accurate than those made at other times of the year, a well-known limitation called the spring predictability barrier. Even so, the combination of deep ocean heat and weakening trade winds gives forecasters growing confidence in El Niño development this summer.
A developing El Niño would shift global rainfall patterns, alter jet stream behavior, and change the odds for drought and flooding across multiple continents. For skiers in the western U.S., the implications for the 2026-27 winter are significant. El Niño winters typically bring wetter-than-normal conditions to the southern tier of the West (good news for California and the Southwest) while the Pacific Northwest and northern Rockies tend to run drier and warmer than average.
The next monthly diagnostic discussion is scheduled for early April 2026.
One thought on “La Niña Fades as NOAA Expects El Niño by Summer With Significant Impact on Winter 2026-27”