March 8, 2025 — A long-awaited La Niña finally arrived in the Pacific Ocean in January. But less than two months later, the picture is rapidly shifting.
The pattern is the foil of the better-known El Niño and is typically known for cooling a vast swath of the Pacific Ocean. But the phenomenon has done little to break the cycle of excessive global heat that dominated during 2024 and has continued into 2025 — except in the United States. And now, signs are emerging that could spell a coming end to the pattern, raising questions about what could come next — including whether yet another record-warm year for the planet could be in the cards.
Meanwhile, a new and unexpected pattern of warming oceans in the eastern Pacific, west of South America, has sent sea temperatures soaring to more than 5 degrees above average. Called a coastal El Niño, or El Niño Costero, the pattern can affect weather near and far. Coastal El Niño events in 2017 and 2023 caused flooding rains and high rates of dengue fever in Peru.