This year's monstrous El Niño heated up the globe, but didn't quite influence weather patterns to produce the kind of rainfall needed to end California's drought, the National Oceanic and Atmospheric Administration said Thursday.
In its monthly update, the agency said a recent return to the normal range for ocean temperatures means the weather phenomenon has come to an end after 15 months.
"There's nothing left," NOAA Climate Prediction Center deputy director Mike Halpert said. "Stick a fork in it, it's done."
Halpert said this El Niño triggered droughts in parts of Africa and India and played a role in a record hurricane season in the Pacific. It also added to man-made warming, as Earth has had 12 straight record hot months and is likely to have its second straight record hot year.
And, this will go down as one of the three strongest El Niños on record, along with 1997-1998 and 1982-83, Halpert said. El Niño is a natural warming of parts of the central Pacific that changes weather worldwide.
Some in California had hoped that the drought would be busted by the El Niño, which generally brings more rain to California and the South. But even at the start, NOAA had cautioned that the rain deficit was too big for the El Niño to fix.
"For one thing, there was more ocean surface warming in the western Pacific and less warming in the eastern Pacific during 2015-16 than 1997-98," Emily Becker of the NOAA wrote in a post on the agency's website. "Also, the amount of warm water under the surface was less during 2015-16 than 1997-98. The atmospheric response during 2015-16 was also generally weaker than during 1997-98.
"In short ... no two El Ninos are alike," she wrote.
And while it was rainy, it wasn't enough, Halpert said. Most of the snow and rainfall stayed to the north, leaving Southern Californians dry for much of the winter.
This week's Drought Monitor Report shows about 21 percent of the state under exceptional drought, the most severe of the weekly report's categories. That figure was at more than 46 percent on year ago, marking significant improvement in northern and extreme southeast California.
More than 83 percent of the state is under moderate drought, down from nearly 100 percent one year ago.
In parts of the central Pacific, ocean temperatures were even hotter and caused more harm than 1997-98, leaving scars "written in the geography and appearance of global reefs for decades to come," said Georgia Tech climate scientist and coral expert Kim Cobb .
"This El Niño has caused some of the worst coral bleaching and death of any event we've ever seen," said NOAA coral reef watch coordinator Mark Eakin. "We've had enough of this."
Earth is now in the neutral part of the natural cycle of El Niños, which includes the cooler flip side, La Nina. But don't expect that to last. NOAA forecasts a 50 percent chance of La Nina by the end of the summer and 75 percent chance by the end of the fall.
La Ninas generally bring more hurricanes to the Atlantic instead of the Pacific, but doesn't have much impact on summer temperature or rain in the United States. It often features drier-than-normal conditions in the U.S. Southwest and wetter conditions in the Pacific Northwest.
In the winter, La Nina often brings lots of rain to parts of Australia and Indonesia and cooler temperatures in parts of Africa, Asia, South America and Canada.
Cobb said her work has found some evidence, not enough to be conclusive, that man-made global warming is causing bigger El Niños more often. Global temperatures with the El Niño that just ended have been about 0.8 degrees warmer (0.45 degrees Celsius) than the 1998 El Niño, according to NOAA.
"This has been a bellwether event," Cobb said.