My calculation uses a 3D integration of GHCNV4 and HadSST3 temperature data. If I use GHCN V4C (corrected data) I get 0.93C for September, whereas if instead I use the uncorrected V4U I get 0.70C. In the first case 2020 is the warmest September ever recorded, while the uncorrected data shows 2016 to be just a bit warmer.
Here are the annual temperature comparisons, where 2020 is simply the average of the first 9 months.
2020 is on track to be the warmest year although only marginally so for the uncorrected data. The values though have reduced slightly since August.
Finally here are the spatial distributions for the Northern and Southern Hemispheres