The planet's average temperature for January-August was 58.5 degrees Fahrenheit (14.7 Celsius), tying the record heat set for that period in 1998, the National Oceanic and Atmospheric Administration has said.

While 1998 was the hottest year through the first eight months, 2005 is the hottest year on record for the full year.

NOAA's National Climatic Data Center also reported: It was the third-hottest August on record with an average temperature for the month of 61.2 degrees F (16.2 C). The hottest August was 1998, followed by 2009.

The meteorological summer – June-August – averaged 61.3 degrees F (16.2 C), making it the second-hottest summer on record worldwide behind 1998.

Meanwhile, a separate report from the National Snow and Ice Data Center said Arctic sea ice cover appears to have reached its minimum extent for the year and is the third-lowest extent recorded since satellites began measuring minimum sea ice extent in 1979.

Arctic sea ice covered an average of 6.0 million square kilometres during August. This is 22 per cent below the 1979-2000 average extent and the 14th consecutive August with below-average Arctic sea ice extent, NOAA reported.

Melting sea ice is part of a pattern of changes atmospheric scientists attribute to global warming, which has been documented in rising temperatures over the last several decades.

Other changes include melting ice in Greenland and Antarctica, which can lead to rising sea levels, a decline in glaciers and changes in weather patterns around the world.

The new climate report noted that August was hotted than normal in eastern Europe, eastern Canada and parts of eastern Asia but cooler-than-average in Australia, central Russia and southern South America.