Day-to-Day Mean Temperature Variabilit—A Monitoring Tool

NOAA's National Climatic Data Center routinely prepares monthly maps of temperature and precipitation anomalies as part of operational climate monitoring activities. Beginning in 1999, departure from normal day-to-day temperature variability maps also have been produced. This variability statistic is computed in order to provide some measure of temperature persistence or variability during a given month. Day-to-day temperature variability may be lower than normal, for example, in months where a single air mass is more persistent than usual, such as occurred over much of the central and eastern U.S. during winter 1998-99. This paper describes the calculation and use of this simple temperature variability statistic in monthly climate monitoring activities. In addition, an analysis of regional and seasonal trends in day-to-day temperature variability evident in the observed record also will be presented.