The U.S. government forecaster has tempered its outlook for El Niño, saying in its monthly report on Thursday that the feared weather phenomenon will be weaker than previously expected.

The U.S. Climate Prediction Center (CPC) said El Niño is expected to develop weakly this month and persist until the Northern Hemisphere spring.

That is a downgrade from last month's forecast for moderate-to-weak conditions.

CPC also delayed timing of its arrival, projecting it will strike in September or October after mostly neutral conditions in August.

The time frame is slightly later than last month's report, which forecast El Niño could influence weather as early as August.

While more feeble than expected, El Niño is still likely to influence weather patterns, potentially wreaking havoc from North and South America to Asia and disrupting global food production.

Its arrival, warming of waters in the equatorial Pacific Ocean, typically raises the chances of favorable planting conditions in South America although it can roil farmers in Asia and Africa where it would deprive crucial harvests of rain.

A fainter-than-expected system may limit some of those extreme conditions though, Donald Keeney, a senior agricultural meteorologist with the Cropcast weather service, told Reuters.

For instance a gentler El Niño reduces the threat of full-scale drought in South East Asia, a key palm oil producing region.

"There will (still) be some areas of dryness, but a half to two thirds of South East Asia will see average rainfall," he said.

Many major areas of food production are still expected to suffer though. Rain has fallen on the northern fringes of West Africa's main cocoa bean-growing area, but missed Ivory Coast and Ghana, the world's top two producers, Kenney said.

Any damage to crops is expected to put further strain on global food supplies and stoke worries about food price inflation. Grain prices have hit record highs this summer as the U.S. corn belt has suffered its worst drought in more than a century this summer.

The latest forecast comes three months after the CPC, part of the National Oceanic Atmospheric Administration, issued its first El Niño watch in June, warning the phenomenon could materialize in the second half of the year.

"Supported by the model forecasts and the continued warmth across the Pacific Ocean, the official forecast calls for the development of most likely a weak El Niño during September 2012, persisting through December-February 2012-13," it said.

El Niño is the warming of sea-surface temperatures in the equatorial Pacific that occurs every four to 12 years, affecting crops from Asia to the Americas and reducing the chances of storms forming in the Atlantic basin during the hurricane season that runs to Nov. 30. (Reporting by Josephine Mason; Editing by Lisa Von Ahn)