La Niña Is Doing Something It Shouldn't

In January 2026, a weak La Niña that barely met the threshold for classification was already starting to fade. By February, new data from NOAA and Australia's Bureau of Meteorology showed that if El Niño arrives in late 2026, the knock-on effects would likely produce record high temperatures in 2027. This La Niña came late, it isn't very strong, and it won't stick around for long. And that is not how La Niña is supposed to behave.

The Climate Seesaw

La Niña and El Niño are opposite phases of the El Niño Southern Oscillation (ENSO), a cycle that has been influencing Earth for tens of thousands of years. Chemical fingerprints preserved in ancient coral fossils and sediment cores stretch back millennia, and written accounts of ENSO-related weather patterns date to the 16th century. The cycle operates like a seesaw: unusually strong easterly trade winds push warm surface water westward toward Asia and Australia during La Niña, allowing cooler water to upwell along the coast of South America. The result is a large region of cooler-than-normal sea surface temperatures in the central and eastern tropical Pacific, which in turn alters atmospheric circulation and shifts jet streams northward.