**Please note, GHCN-Monthly provides climatological observations for four elements; monthly mean maximum temperature, minimum temperature, mean temperature, and monthly total precipitation. Precipitation are available in version 2, monthly mean maximum and minimum temperature in version 3, and monthly mean temperature is also now available in the Version 4 BETA release. Users of monthly mean temperature should use the most recently available fully operational version except in some cases (e.g., when reproducing previous studies that used a previous version).** Since the early 1990s the Global Historical Climatology Network-Monthly (GHCN-M) dataset has been an internationally recognized source of data for the study of observed variability and change in land surface air temperature. It provides monthly mean temperature data for 7280 stations from 226 countries and territories, ongoing monthly updates of more than 2000 stations to support monitoring of current and evolving climate conditions, and homogeneity adjustments to remove non-climatic influences that can bias the observed temperature record. The release of version 3 monthly mean temperature data in 2011 introduced a number of improvements and changes from the previous release that included consolidating "duplicate" series, updating records from recent decades, and the use of new approaches to homogenization and quality assurance.