Combustion of woody material produces and releases water, but the effects of this water on the atmospheric circulation created by a wildfire are rarely recognized, let alone understood. This paper presents observational data and basic physical arguments to support the hypothesis that this moisture can constitute a large portion of the total water content in a fire plume. Calculations demonstrate the effects this moisture could have on fire-driven atmospheric circulations, specifically updrafts and downdrafts, on time and space scales important for fire behavior and fire-fighter safety. This study should be considered exploratory; it does not prove the presence or importance of this moisture, but seeks to show that further study is needed to determine how much moisture a fire adds to the air, and whether that amount is or is not important. © IAWF. Reproduced from the International Journal of Wildland Fire (Brian E. Potter, 2005) with the kind permission of CSIRO PUBLISHING on behalf of the International Association of Wildland Fire. (http://www.publish.csiro.au/journals/ijwf/).