The variable nature of wind speed and direction affects the critical zones of chemical incidents (spills and effluents). We describe a method to develop a GIS-based “plume rose” using its corresponding wind rose to map the areas that might be affected by a chemical release incident. The plume rose can thus be used in the preparation and response phases of emergency management for an industrial chemical incident. In this study, we examine an industrial region in Bangalore, India and show that seasonal variation in winds significantly change the nature (size and direction) of the plume rose. The annual plume rose is coarse and inadequate for effective planning and response for this location. Thus, the GIS-based monthly plume rose is more effective for planning and response management.