From the National Oceanic and Atmospheric Administration:
In the span of 141 years of climate records, there has never been a warmer January than last month, according to scientists at NOAA’s National Centers for Environmental Information.
What’s more, the temperature departure from average was the highest monthly departure ever recorded without an El Niño present in the tropical Pacific Ocean. January 2020 marked the 44th consecutive January and the 421st consecutive month with temperatures, at least nominally, above the 20th-century average.
The January global land and ocean surface temperature was the highest on record at 2.05 degrees F (1.14 degrees C) above the 20th-century average. This surpassed the record set in January 2016 by 0.04 of a degree F (0.02 of a degree C).
The four warmest Januaries documented in the climate record have occurred since 2016; the 10 warmest have all occurred since 2002.
Breaking the month down by hemispheres, the Northern Hemisphere also had its warmest January on record, at 2.70 degrees F (1.50 degrees C) above average. The Southern Hemisphere had a departure of 1.40 degrees F (0.78 of a degree C) above average — its second-warmest January on record after January 2016.