The variability of starch between and within plant species causes difficulties in predicting functional performance in food processing and human nutrition. The variability of starch results from diversity of structure, which reflects the genetics of starch biosynthesis and environmental influences during plant growth. Variability in growth conditions is increasing from one year to the next and is now considered a major factor that affects the quality of cereal grains. Our research is aimed at increasing the understanding of environmental factors that influence variability of starch structure, and in turn starch properties that affect cereal grain quality. Starch was isolated from grain harvested from five commercial Australian wheat varieties that were grown in five different climatic regions of Australia in two years. Analyses were performed on the isolated starch to examine the extent to which genotype, growth location and year influenced variability of physical and chemical properties of starch. The properties that were examined included: total starch content of the grain, total and free amylose content of the starch, granule size distribution, amount of protein associated with starch granules, and starch swelling power. Statistical analysis of variance indicated that all of these properties for each genotype were significantly affected (significant at p < 0.001) by growth location and year. Specific correlations were also identified between starch variability and characteristics of the growth locations (soil properties, rainfall, atmospheric temperature and number of clear days). Interactions between growth year and location contributed significantly to the variance in total amylose content and starch swelling power, whereas interactions between year and genotype were significant for total and free amylose and the amount of protein associated with starch granules.