Geographic Information System (GIS) based computer applications are becoming increasingly popular for delivering, visualizing and analyzing spatial databases. Driven by advances in computing technologies, GIS applications are increasingly used by non- GIS experts as knowledge support tools that allow instant access and visualization of spatial data across the internet. The American Viticultural areas of Texas (AVATXIS) is an example of a web-based GIS tool that we have developed to help viticulturists better understand wine growing regions in Texas. The application allows users to spatially query and visualize a range of edaphic and climatic factors that influence vine growth and grape production. By providing growers a wide variety of climatic and edaphic data sets and an intuitive, easy to use interface for visualizing and downloading this data, AVATXIS serves as an effective tool for characterizing the Texas wine regions. Research in the field of viticulture states that ?Climate governs whether grapes will survive and ripen, what varieties do best where, and some of the characteristics of the resulting wines?. For AVATXIS, a number of specific climate indices critical to wine production were identified through the current viticulture literature and by consulting with experts. These indices include monthly summaries of maximum, minimum and mean temperature, precipitation and Growing Degree-Days (GDD). Publicly available climate data was used to create novel GIS layers for each of these indices. Similarly the importance of soil type to vine growth is recognized, but its relationship to wine quality remains controversial. Publicly available soil data were used to create GIS layers representing simple soil indices (pH, soil texture, depth to bedrock, permeability, available water capacity, and bulk density) useful to the wine grower. These climate and soils data form the central database used by AVATXIS. The intuitive, user interface allows any combination of these GIS layers to be rapidly retrieved and visualized through a standard web-browser by any user of the AVATXIS system.