Merrimac is a census-designated place (CDP) in Montgomery County, Virginia, United States.

According to one source, Merrimac was so named because coal from area mines was used on CSS Virginia (formerly USS Merrimack).

[4] The Linkous-Kipps House and Montgomery Primitive Baptist Church are listed on the National Register of Historic Places.

[6] According to the United States Census Bureau, the CDP has a total area of 1.8 square miles (4.7 km2), all of it land.

The climate in this area is characterized by hot, humid summers and generally mild to cool winters.