October 1 to 31 With an average coast-to-coast precipitation of 0.54 inches , Contiguous U.S. Precipitation – October this is easily the driest month over the contiguous United States since reliable records began in 1895 Winston, Jay S.; ‘The Weather and Circulation of October 1952: The Driest Month on Record in the United States’; Monthly Weather Review; 80(10); pp.