Last month was the warmest May for the Earth on record, according to a climate report released Monday by the National Oceanic and Atmospheric Administration.
The heat was fueled by unusual warmth in the oceans, which make up more than 70% of the Earth's surface.
"The majority of the world experienced warmer-than-average monthly temperatures, with record warmth across eastern Kazakhstan, parts of Indonesia and central and northwestern Australia," the report from NOAA's National Climatic Data Center noted. "Scattered sections across every major ocean basin were also record warm."
The combined average temperature over the entire globe in May 2014 was 59.93 degrees Fahrenheit, which was 1.33 degrees above the 20th-century average, NOAA said.
The USA was warm in May, but far from a record. A report last week noted that May 2014 was the nation's 32nd warmest May on record.
Global temperature records go back to 1880.
It also marked the 351st consecutive month with a global temperature above the 20th-century average.
Last week, separate climate data sets from NASA and the Japan Meteorological Agency also found that May was the warmest on record.
For the spring 2014 season, defined as the months of March, April and May, it was the second warmest spring on record. For the year to date, it's been the fifth warmest on record, so far, the climate center reported.
El Niño, a warming of tropical Pacific Ocean water that affects climate and weather patterns around the world, was not present yet in May, the NCDC reported. However, the Climate Prediction Center estimates that there is about a 70% chance that El Niño conditions will develop during the summer of 2014 and an 80% chance it will develop during the fall and winter.
The two warmest years on record, 1998 and 2010, occurred during El Niños.