[2][3] Northwood is part of the Mason City Micropolitan Statistical Area.

[6] According to the United States Census Bureau, the city has a total area of 3.76 square miles (9.74 km2), all land.

There were 990 housing units at an average density of 248.4 per square mile (95.9/km2).

Hispanic or Latino persons of any race comprised 3.2% of the population.

There were 1,004 housing units at an average density of 267.0 per square mile (103.1/km2).

35.0% of all households were made up of individuals, and 17.1% had someone living alone who was 65 years of age or older.

There were 982 housing units at an average density of 259.7 per square mile (100.3/km2).

36.0% of all households were made up of individuals, and 20.6% had someone living alone who was 65 years of age or older.

[12] Humid continental climate is a climatic designation typified by large seasonal temperature differences, with warm to hot (and often humid) summers and cold (sometimes severely cold) winters.