The chances have increased over the past month that the much-feared El Nino weather phenomenon, which can wreak havoc on global crops, will strike this year, the federal U.S. forecaster said Thursday.

In its monthly report, the Climate Prediction Center, an agency of the National Weather Service, said neutral conditions will prevail through the spring. But the forecaster raised the likelihood of the weather pattern developing over the summer to more than 65 percent.

In April, it said it saw a 50 percent chance of the weather pattern developing by the summer.

Global weather forecasters in recent months have increased the likelihood of El Nino, a warming of sea-surface temperatures in the Pacific, heightening uncertainty in global commodity and energy markets.

(Reporting by Chris Prentice; Editing by Nick Zieminski)