Sea ice covers Cape Cod Bay as viewed from Rock Harbor Beach, Cape Cod, in Orleans, MA, on Wed., Jan. 3, 2018. Image credit: Scott Eisen/Getty Images.
© Scott Eisen/Getty Images.
Sea ice covers Cape Cod Bay as viewed from Rock Harbor Beach, Cape Cod, in Orleans, MA, on Wed., Jan. 3, 2018.
From Dr. Roy Spencer:

UAH Global Temperature Update for January, 2018: +0.26 deg. C

Coolest tropics since June, 2012 at -0.12 deg. C.

The Version 6.0 global average lower tropospheric temperature (LT) anomaly for January, 2018 was +0.26 deg. C, down from the December, 2017 value of +0.41 deg. C:

UAH satellite data global cooling

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 as has the distinction between calendar months.

The global, hemispheric, and tropical LT anomalies from the 30-year (1981-2010) average for the last 13 months are:

2017 01 +0.33 +0.31 +0.34 +0.10
2017 02 +0.38 +0.57 +0.20 +0.08
2017 03 +0.23 +0.36 +0.09 +0.06
2017 04 +0.27 +0.28 +0.26 +0.21
2017 05 +0.44 +0.39 +0.49 +0.41
2017 06 +0.21 +0.33 +0.10 +0.39
2017 07 +0.29 +0.30 +0.27 +0.51
2017 08 +0.41 +0.40 +0.42 +0.46
2017 09 +0.54 +0.51 +0.57 +0.54
2017 10 +0.63 +0.66 +0.59 +0.47
2017 11 +0.36 +0.33 +0.38 +0.26
2017 12 +0.41 +0.50 +0.33 +0.26
2018 01 +0.26 +0.46 +0.06 -0.12

Note that La Nina cooling in the tropics has finally penetrated the troposphere, with a -0.12 deg. C departure from average. The last time the tropics were cooler than this was June, 2012 (-0.15 deg. C). Out of the 470 month satellite record, the 0.38 deg. C one-month drop in January tropical temperatures was tied for the 3rd largest, beaten only by October 1991 (0.51 deg. C drop) and August, 2014 (0.41 deg. C drop).

The last time the Southern Hemisphere was this cool (+0.06 deg. C) was July, 2015 (+0.04 deg. C).

The linear temperature trend of the global average lower tropospheric temperature anomalies from January 1979 through January 2018 remains at +0.13 C/decade.

The UAH LT global anomaly image for January, 2018 should be available in the next few days here.

The new Version 6 files should also be updated in the coming days, and are located here:

Lower Troposphere:
Lower Stratosphere:


Global Temperature Report: January 2018 Temperatures fall as La Niña's effects are felt
monthly global lower troposphere temp

Global climate trend since Nov. 16, 1978: +0.13 C per decade
January temperatures (preliminary)

Global composite temp.: +0.26 C (about 0.47 degrees Fahrenheit) above 30-year average for January.
Northern Hemisphere: +0.46 C (about 0.83 degrees Fahrenheit) above 30-year average for January.
Southern Hemisphere: +0.06 C (about 0.11 degrees Fahrenheit) above 30-year average for January.
Tropics: - 0.12 C (about 0.22 degrees Fahrenheit) below 30-year average for January.
December temperatures (revised):

Global Composite: +0.41 C above 30-year average
Northern Hemisphere: +0.50 C above 30-year average
Southern Hemisphere: +0.33 C above 30-year average
Tropics: +0.26 C above 30-year average
(All temperature anomalies are based on a 30-year average (1981-2010) for the month reported.)
Notes on data released Feb. 1, 2018:

A La Niña equatorial Pacific Ocean cooling event is making itself felt in the atmosphere, dropping average temperatures in the tropics to their lowest point since June 2012 (-0.15 C), and temperatures in the Southern Hemisphere (+0.06 C) to their coolest since April 2015 (-0.01 C), according to Dr. John Christy, director of the Earth System Science Center (ESSC) at The University of Alabama in Huntsville.

The drop in tropical temperatures (0.38 C) from December to January tied for the third largest one-month drop in the 470 months of satellite temperature data. The largest was 0.51 C from September to October 1991, which followed the eruption of the Mount Pinatubo volcano in the Philippines. The second largest (0.41 C) was from July to August 2014.

lower troposphere 2018 temperatures
Compared to seasonal norms, the coldest spot on the globe in January was near the Tsambagarav-Uul National Park, in eastern Mongolia. Temperatures there were 3.22 C (about 5.80 degrees Fahrenheit) cooler than seasonal norms.

Compared to seasonal norms, the warmest place on Earth in January was near Wrangel Island, in the East Siberian Sea. Tropospheric temperatures there averaged 4.75 C (about 8.55 degrees Fahrenheit) warmer than seasonal norms.

As part of an ongoing joint project between UAH, NOAA and NASA, Christy and Dr. Roy Spencer, an ESSC principal scientist, use data gathered by advanced microwave sounding units on NOAA and NASA satellites to get accurate temperature readings for almost all regions of the Earth. This includes remote desert, ocean and rain forest areas where reliable climate data are not otherwise available.

The satellite-based instruments measure the temperature of the atmosphere from the surface up to an altitude of about eight kilometers above sea level. Once the monthly temperature data are collected and processed, they are placed in a "public" computer file for immediate access by atmospheric scientists in the U.S. and abroad.

The complete version 6 lower troposphere dataset is available here:

Archived color maps of local temperature anomalies are available on-line at:

Neither Christy nor Spencer receives any research support or funding from oil, coal or industrial companies or organizations, or from any private or special interest groups. All of their climate research funding comes from federal and state grants or contracts.