The Atmospheric Layer Temperature Climate Data Record (CDR) dataset is a monthly analysis of the tropospheric and stratospheric data using temperature sounding microwave radiometers flown on polar-orbiting weather satellites providing an important record of upper atmosphere temperatures by merging data from the older Microwave Sounding Unit (MSU) and the new Advanced Microwave Sounding Units (AMSUs). The instruments measure the brightness temperature (Tb) for each channel and corresponds to an average temperature of the atmosphere averaged over that channel's weighting function. Global average and global anomaly maps on a 2.5 x 2.5 degree resolution are produced from each month's data from both the MSU and the AMSU for over a 31 year period (1978-2011) for each channel (layer); the Temperature Lower Troposphere (TLT); the Temperature Middle Troposphere (TMT); the Temperature Troposphere/Stratosphere (TTS) ; the Temperature Lower Stratosphere (TLS). UAT 4 Layer MW data is important to continue into the future to ensure the existence of a high-quality record of atmospheric temperatures for climate change detection and climate model verification activities. The data are available in netCDF-4 file format with variables containing standard deviation, quality flags, and projection information and will be updated monthly.