Globally, October 2019 was the second warmest October since records began in 1850.
The global mean temperature was 0.99 ± 0.06 °C above the 1951 to 1980 average. This is equivalent to being 1.38 ± 0.07 °C above the 1850 to 1900 average that is frequently used as a benchmark for the pre-industrial period.
Though October 2019 was nominally slightly cooler than October 2015 (by ~0.01 °C), this difference is within the margin of error, so 2019 and 2015 are effectively tied.
Temperature anomalies in October 2019 showed a marked uptick from September 2019. It is too early to know if this is merely 1-month fluctuation or the start of a short-term trend.
In 2015, the jump to a warm October preceded an exceptionally warm December through April period that ultimately allowed 2016 to the warmest year observed. However, in the 2015/2016 period an exceptionally strong El Niño was present. Such conditions are not present currently and are not expected to arise during the next few months.
Spatially, October 2019 was marked by extreme warmth across the Arctic, significant warmth across much of Asia, Europe, the Middle East, and parts of Australia. Unusually warm conditions were also present in the Indian Ocean and the Northern Pacific. Extraordinary cold was present in parts of North America, including in some places that saw record-breaking monthly low averages for October.
Over land regions, 2019 was also the 2nd warmest October, coming in as 1.46 ± 0.09 °C above the 1951 to 1980 average. It was similarly the second warmest October in the oceans, recorded as 0.59 ± 0.07 °C above the 1951 to 1980 average. In both cases, the warmest October occurred in 2015.
After 10 months, the Earth in 2019 has been marked by above average temperatures nearly everywhere, with the notable exception of a relatively cool conditions in part of North America.
So far, only three of ten months in 2019 have been the warmest recorded, though all of the months in 2019 have been within the top 5 warmest.
It appears nearly certain (99% likelihood) that 2019 will conclude as the second-warmest year since measurements began in 1850, behind only the exceptional warmth of 2016.