Cluster analysis has been used for many years in weather and climate research but most applications have concentrated on a handful of techniques. However, the subject is vast with many methods scattered across a number of literatures, and research on new variants continues. This paper describes a few of these new developments, concentrating on those that have appeared in the statistical and atmospheric science literatures. Their relevance to applications in weather and climate is discussed. (C) 2009 Elsevier Ltd. All rights reserved.