Last month's average global temperature made it the second-warmest May since record-keeping began in 1880, according to the National Oceanic and Atmospheric Administration (NOAA).

"The combined average temperature over global land and ocean surfaces for May was second warmest on record for May, behind 2010, at 59.79°F (15.46°C) or 1.19°F (0.66°C) above the 20th century average,” NOAA said in its latest monthly analysis.

"Most areas of the world experienced much warmer-than-average monthly temperatures, including nearly all of Europe, Asia, northern Africa, most of North America and southern Greenland. Only Australia, Alaska and parts of the western U.S.-Canadian border region were notably cooler than average," NOAA said in its summary of the data.