September 2012 Blended Land and Sea Surface Temperature Percentiles (source: NOAA's National Climatic Data Center)

The world just experienced its warmest September ever, tied with a 2005 record, the NOAA said on Monday.

The average global combined temperatures from land and ocean were 1.21°F above average,  another extreme in the world under climate change, according to the latest State of the Climate report from NOAA's National Climatic Data Center.

The warm September record follows a trend of land and ocean warming, with the first nine months having the eighth warmest global land and ocean temperature in record keeping history. 

September 2012 was also the month in which the Arctic had its smallest sea ice extent on record. 

Extremes were recorded on a national level as well.

"The January-September period was the warmest first nine months of any year on record for the contiguous United States. The national temperature of 59.8°F was 3.8°F above the 20th century average," the analysis states.

The warm season in the U.S., April to September, was also the warmest such period ever.  

source: NOAA's National Climatic Data Center