New Hampshire has a humid continental climate with cold winters and warm, humid summers. Major surface flows include the Connecticut River, which forms the western border of the state, and the Merrimack River, which flows through the central part of the state. The Pemigewasset, Saco, and Androscoggin Rivers are also significant. There are numerous reservoirs and dams in the state, including the Amoskeag Dam on the Merrimack River. Hydrology in New Hampshire is influenced by precipitation patterns, which vary widely across the state. Snowpack in the winter months is a major source of water for rivers and streams in the spring and summer. The state's many watersheds, including the Connecticut River watershed, play a critical role in determining flow conditions.