Roy is an unincorporated community and a Census-designated place in Fergus County, Montana, United States. The community is located along U.S. Highway 191 in northeastern Fergus County. Although it is unincorporated, Roy has a post office, with the ZIP code of 59471. As of the census of 2010, there were 108 people.Roy has a semi-arid climate with cold winters except when moderates by chinook influences that will typically push maximum temperatures over 50 °F or 10 °C on seventeen days during winter and twelve days each in November and March. Spring is mild and frequently thundery, whilst summer days are hot – sometimes very hot – but nights are usually pleasantly cool.Precipitation is fairly scarce, mostly coming from thunderstorms during late spring and summer, whilst snowfall averages 43 inches or 1.09 metres but significant falls occur on only a minority of winter days. However, during the cold winter of 1977–78, cover reached 56 inches or 1.