Last month was the hottest August in modern history, in the latest sign of an unusually warm year across the world's land and sea surfaces, US government scientists said Thursday.

Record-breaking warmth was seen across much of South America and parts of Africa, the Middle East, Europe and Asia, said the report by the National Oceanic and Atmospheric Administration.

The most scorching August on the planet in 136 years was also the sixth month this year to have broken a monthly temperature record, putting 2015 on pace to beat 2014 as the warmest year ever, scientists said.

"The world is basically dominated by areas that are record warm or much warmer than average," said Deke Arndt, monitoring branch chief of NOAA's National Centers for Environmental Information.

"This applies really to almost every continent, and to large portions of every ocean basin."

Researchers have calculated it is 97 percent likely that 2015 will be the warmest ever recorded, Arndt said.

Other months this year that have broken records were February, March, May, June, and July, said the NOAA report.

The record continued a worrying trend of warming, which many scientists say is caused by fossil-fuel burning and is exacerbated by the presence of El Nino, which has a warming effect on some parts of the world's oceans.

Much of August's warmth was driven by the world's water.

"Large portions of the seven seas (where temperature records are available) recorded much-warmer-than-average temperatures, with some locations across all oceans experiencing record warmth," said the report.

The August globally-averaged sea surface temperature was 1.40 Fahrenheit (0.78 Celsius) above the 20th century average.

That marked the "highest temperature for any month in the 1880-2015 record, surpassing the previous record set in July 2015 by 0.07 Fahrenheit (0.04 Celsius)," according to NOAA.