Windsor is an incorporated town in Sonoma County, California, United States. The population was 26,801 as of the 2010 census.
Windsor is located on U.S. Route 101 in the Russian River valley, about 5 miles (8.0 km) southeast of Healdsburg, California.
According to the United States Census Bureau, the town has a total area of 7.3 square miles (18.9 km²), 99.66% of it land and 0.34% of it water. Windsor is 2 miles (3.2 km) from the Russian River.