According to the United States Census Bureau, the city has a total area of 3.96 square miles (10.26 km2), all land.

[7] Rock Rapids has a humid continental climate (Koppen Dfa), with cold winters and hot summers.

There were 1,145 housing units at an average density of 272.0 per square mile (105.0/km2).

Hispanic or Latino persons of any race comprised 3.5% of the population.

There were 1,207 housing units at an average density of 304.8 per square mile (117.7/km2).

33.7% of all households were made up of individuals, and 18.4% had someone living alone who was 65 years of age or older.

There were 1,160 housing units at an average density of 293.1 per square mile (113.2/km2).

31.3% of all households were made up of individuals, and 17.6% had someone living alone who was 65 years of age or older.

Rock Rapids is served by the Central Lyon Community School District.

Island Park features a Rock Island railroad trestle that has been resurfaced as part of a new recreation trail and a museum in the nearby retired depot.