By Climatologist Dr. Roy Spencer
The Version 6.0 global average lower tropospheric temperature (LT) anomaly for September, 2018 was +0.14 deg. C, down a little from +0.19 deg. C in August:
Global area-averaged lower tropospheric temperature anomalies (departures from 30-year calendar monthly means, 1981-2010). The 13-month centered average is meant to give an indication of the lower frequency variations in the data; the choice of 13 months is somewhat arbitrary… an odd number of months allows centered plotting on months with no time lag between the two plotted time series. The inclusion of two of the same calendar months on the ends of the 13-month averaging period causes no issues with interpretation because the seasonal temperature cycle has been removed, and so has the distinction between calendar months.
This was the coolest September in the last 10 years in the global average.