Wyarno is an unincorporated community in central Sheridan County, Wyoming, United States. It lies along Wyoming Highway 336, approximately 10 miles east of the city of Sheridan, the county seat of Sheridan County. Although Wyarno is unincorporated, it has a post office, with the ZIP code of 82845. Public education in the community of Wy…Wyarno is an unincorporated community in central Sheridan County, Wyoming, United States. It lies along Wyoming Highway 336, approximately 10 miles east of the city of Sheridan, the county seat of Sheridan County. Although Wyarno is unincorporated, it has a post office, with the ZIP code of 82845. Public education in the community of Wyarno is provided by Sheridan County School District #2.