WASHINGTON (AFP) - Last month was the hottest August on record for global average temperatures over land and ocean surfaces, the US National Oceanic and Atmospheric Administration (NOAA) said Thursday.

If the trend continues, 2014 could set records for planet-wide heat, raising fresh alarm at the pace of global warming and the burning of fossil fuels.

The month's temperature was 0.75 deg C above the 20th century average, the agency said in its monthly climate report.

"It was the largest departure from average of any month on record," said Jake Crouch, a climate scientist at NOAA, noting that record-keeping began in 1880.

The month's average land and ocean surface temperature was 16.35 deg C. The 20th century average for August is 15.6 deg C.

The period between January and August was also the third warmest on record, said the report.

"If we continue a consistent departure from average for the rest of 2014, we will edge out 2010 for the warmest year on record," Crouch told reporters.

"Another way to think of that, if the next four months - September through December - if each of those months rank among the five warmest on record, 2014 will be the warmest year on record for the globe," he added.

Most of the global oceans were much warmer than average last month, Crouch said.

On land, temperatures across the United States were near average, while parts of Europe, central Asia and Australia were near average or slightly cooler than average.

Even the arrival of El Nino, leading to warmer waters in the Equatorial Pacific and a wetter-than-normal season, is not likely to be enough to re-establish disappearing water reservoirs on the US west coast due to a devastating drought in recent years, experts said.

"This year's El Nino is probably not going to be the savior for ending the drought in California," said Alan Haynes, service coordination hydrologist at NOAA's weather service.

"We don't expect it to be in that drought-busting category."