Using satellite observations, climatologists from the University of Alabama in Huntsville determined the global average temperature last month was just under 1 degree Fahrenheit above the 30-year average for January.
This eclipses the previous record of 0.88 degree above the satellite-era average set during January 1998, which was near the peak of the strongest El Niño ever measured.
Using data gathered by advanced microwave instruments on NOAA and NASA satellites, atmospheric scientists can determine accurate temperature readings for almost all regions of the world.
This includes remote deserts, oceans and rain forests, where reliable climate data are not otherwise available.
The satellite-based instruments measure the temperature of the atmosphere from the surface up to an altitude of about 25,000 feet above sea level.
But such readings only go back about 30 years to the early days of satellite monitoring, limiting the ability to determine long-term trends with the technique.