Annville gets warm to hot summers and cold winters.

As of the 2000 census,[5] there were 4,518 people, 1,452 households, and 917 families residing in the township.

There were 1,556 housing units at an average density of 986.6 per square mile (380.9/km2).

The racial makeup of the township was 95.40% White, 1.08% African American, 0.02% Native American, 1.24% Asian, 0.11% Pacific Islander, 0.97% from other races, and 1.17% from two or more races.

29.1% of all households were made up of individuals, and 11.8% had someone living alone who was 65 years of age or older.