This visualization, built with data from May 26, 2026, shows global sea surface temperature anomalies through the lens of the Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis, which compares current measurements with past Multiscale Ultrahigh Resolution (MUR) climatology. Areas in orange and red are warmer than the average for this time of year. Note the warmer than average temperatures in the eastern equatorial Pacific Ocean, indicating possible development of an El Niño event.
El Niño is a natural climate cycle that occurs every two to seven years and lasts nine to twelve months. During such an event, easterly trade winds (which blow from the Americas toward Asia) falter and can even turn around into westerlies, causing the surface waters in central and eastern tropical Pacific Ocean to become significantly warmer than usual. Great masses of warm water move from the western Pacific toward the Americas. The change in winds also reduces the upwelling of cooler, nutrient-rich waters from the deep — shutting down or reversing some ocean currents around the equator and along the west coast of South and Central America.
The circulation of air above the tropical Pacific Ocean responds to this redistribution of ocean heat. The typically strong high-pressure systems of the eastern Pacific weaken, changing the balance of atmospheric pressure across the eastern, central, and western Pacific. While easterly winds tend to be dry and steady, Pacific westerlies tend to come in bursts of warmer, moister air. Because of the vastness of the Pacific basin, these wind and humidity changes get transmitted around the world, disrupting circulation patterns such as jet streams.