NOAA announced this morning that September 2019 was tied with 2015 as the warmest September on record globally. In addition, the year-to-date temperature through September is the second warmest on record. Some additional statistics from NOAA:
The September temperature across global land and ocean surfaces was 1.71°F above the 20th century average of 59.0°F (tied with 2015)
The 10 warmest Septembers have all occurred since 2005, with the last five years (2015-2019) being the five warmest Septembers on record.
September 2019 also marks the 43rd consecutive September and the 417th consecutive month with temperatures above the 20th century average.
The year-to-date temperature (Jan-Sep) across global land and ocean surfaces was 1.69°F above the 20th century average of 57.5°F. Only January-September 2016 was warmer (+1.91°F).
The U.S. had its second warmest September on record, but combining the data for the rest of the continent indicates that North America had its warmest September on record.
NASA’s independent calculations concluded that September 2019 was the globally second warmest September on record, trailing September 2016. NASA’s and NOAA’s calculations differ, as NASA’s are extended to account for temperature changes at the poles. NOAA does not use any extrapolation to account for sparse station density at the poles. Effectively, NASA assumes that the poles are warming at the rate of nearby stations, while NOAA assumes they are warming at the mean global rate.
Climate Central combines the NASA and NOAA calculations for the above Hottest Years graphic to highlight the amount of warming from a pre-industrial baseline of 1881-1910, in relation to the 2°C threshold from the 2015 Paris Agreement. The Climate Central calculation indicates that 2019 is the second warmest year on record through the end of September.