Centers that track surface temperatures have reported their data for May, and they both found it to be the warmest such month on record. NASA found that May had an average global temperature that was 1.38 degrees F above average, making it the warmest such month.
The Japanese Meteorological Agency’s separate analysis also found both May and the meteorological spring months of March through May to be the warmest on record. These results are preliminary, with the data from both agencies subject to revision. NASA posted a note on its surface-temperature data website Tuesday that said "missing data" from China has not yet arrived, and that their data is not "directly comparable" to previous records.
Later this week, the National Oceanic and Atmospheric Administration (NOAA) will release their global numbers, which typically closely match the other centers, but sometimes differ slightly in rankings. According to the World Meteorological Agency, all but one of the 10 warmest years on record have occurred in the 21st century.