Dense cold air tends to settle into valleys under certain weather conditions and is believed to have a strong influence on the function and biodiversity of forest ecosystems. This presentation will examine recent temperature data collected from around the Hubbard Brook Experimental Forest to understand several aspects of cold air pools: when and how often they occur, how deep they can be, how cold they get, their seasonality, and the large scale weather patterns that most often cause them to form and dissipate.