When the invasion went ahead on July 10, 1943, rough seas disorganized the attacking boat waves, and the soft sand was an impediment to movement. However, the location was poorly defended and the Allies were able to consolidate their position in a day or two and move further inland.
Mitcham, Samuel M. and Stauffenberg, Friedrich von (2007): The Battle of Sicily: How the Allies Lost Their Chance, Stackpole Books, ISBN0-8117-3403-X (Extract).