In 137 years of modern record-keeping, May 2017 was found to be the second warmest May. The records were analyzed by scientists at NASA's Goddard Institute for Space Studies (GISS) in New York. The scientists found this by a monthly analysis of global temperatures at Institute.
The scientists found that the last month was 0.88 degrees Celsius warmer. It was warmer than the mean May temperature from 1951-1980. The top irregularities in temperatures of May have happened in the last two years only. 2016 was the hottest year on record. It was at 0.93 degrees Celsius warmer than the May mean temperature. The temperature of May 2017 was 0.05 degrees cooler than the temperature of May 2016.
The temperature of May 2017 was very closely warm to the third warmest May on records. May 2017 was just 0.01 degrees Celsius warmer than the third warmest May that happened in the year 2014.