Compared to 1990-1995 averages, the summer of 2000 had an atypically high number of high Haines Index days in the northern Rocky Mountains. The summer of 1999, however, had still more high Haines Index days in the region. In contrast, the area burnt by wildfires in this region in 2000 was significantly greater than that in 1999. This could be construed as a failure of the Haines Index, but there are other possible explanations. In particular, the Haines Index is not suitable on days with high winds, and if the 2000 fires were wind-driven on many days, then the Haines Index was not appropriate for those days. The authors examine data from three large fires in southwestern Montana in August 2000, comparing daily area burnt with nearby daily Haines Index values for only those days where winds were relatively calm. If the results show a positive correlation between Haines Index and burn area, it will support the validity of the Index as a measure of the potential spread rate for fires on low wind days (i.e., plume dominated fires).