[3] According to the U.S. Census Bureau, the township has a total area of 31.3 square miles (81 km2), all of which is land.

Greenwich Township has a humid continental climate (Dfa/Dfb) and the hardiness zones are 6a and 6b.

The average monthly temperatures in Krumsville range from 29.0 °F in January to 71.9 °F in July.

At the 2000 census there were 3,386 people, 1,245 households, and 957 families living in the township.

The Appalachian National Scenic Trail passes through the northwest corner of the township and most of the Pennsylvania State Game Lands Number 182 is located near the southwest corner.

[8] This anomaly in pronunciation often leads to confusion with natives of Greenwich, London, New York City, and other areas containing a Greenwich Township, such as Huron County, Ohio.