It’s official, El Niño has developed in the tropical Pacific Ocean; now what?

NOAA’s National Weather Service announced Thursday, June 11 that El Niño has developed in the tropical Pacific, issuing an El Niño Advisory for the weather phenomenon to persist through 2026 and into 2027. 

NWS forecasters predict there is a 63% chance of sea surface temperatures to exceed 2.0°C, or 3.6°F, in the Nino-monitored region of the Pacific.

If this threshold is surpassed, NOAA considers the event a “very strong” El Niño, according to NOAA. Prior to 2015-16, the other prominent +2°C El Niño events in modern records occurred in 1982–83 and 1997–98.

What does El Niño’s formation mean?

According to NOAA, El Niño tends to be strongest during the winter months, with global impacts typically most significant in the northern hemisphere winter. 

During a typical El Niño winter, the jet stream over the north Pacific Ocean tends to shift southward, bringing the storm track over the southern tier of the U.S., NOAA said.

“Every El Nino is not the same; each one is unique with its own imprint on our weather,” Ken Graham, Director at NOAA’s National Weather Service (NWS) said. “Advanced monitoring and an improved understanding of El Nino patterns allow the NWS to better predict and better prepare the public and our core partners for what is to come.”

Usual impacts of El Niño in Colorado:

• Eastern Plains and Front Range: Stronger El Niño events are historically linked to higher-than-average winter snowfall and increased seasonal precipitation.
• Southern and western Colorado: Often experiences more consistent boosts to monsoon activity and tropical moisture during warmer months.
• Northern mountains: Can sometimes miss out on the largest storms due to their typical reliance on northern/westerly weather patterns

Usual impacts of El Nino across the U.S.:

• Stronger upper-level winds that tend to suppress storm and hurricane development in the Atlantic Basin, while weaker winds tend to enhance tropical development in the eastern and central Pacific basins.
• Stormier weather is more likely in the Southern U.S., with chances of both rain and snow increased during El Nino winters.
• High tide flooding could become a higher risk in parts of the U.S., especially on the West Coast. 
• Changes in the migration of fish and other oceanic organisms, with warm water species moving north while cold water species move farther north or into deeper waters. These behavioral changes impact growth, survival, and reproduction.
• Past El Nino episodes have also enhanced the formation of harmful algal blooms along the U.S West Coast.