South Mountain, the northern extension of the Blue Ridge Mountains, makes up the western border of Adams County. Strasbaugh Hill, the highest elevation in Adams County at 1,975 feet, is located in the South Mountain section of the county. The fruit belt is located in the foothills of South Mountain. Most of Adams County is located in the Piedmont Plateau, a rich agricultural land that includes the Gettysburg Newark Lowlands.

Adams County covers 522 square miles (or 334,000 acres) of land.

• 13,819 acres preserved by the Adams County Land Conservancy (2025)

• 5,700 acres included in the Gettysburg National Military Park (National Park Service, 2025)

• 183,000 acres of farms (USDA, 2022)

• 20,000 acres of orchards (Adams County Fruit Growers Association, 2025)

1,270 miles of streams flow through Adams County, and almost all of these streams originate within the county. 30% of these streams (indicated in orange on the map) are impaired for water quality. Adams County is divided into two major watersheds. The water that drains from the land in the northeastern half of the county flows east into the Susquehanna River. The water that drains from the southwestern half of the county flows south toward the Potomac River. The Potomac and Susquehanna River Watersheds are subdivided into smaller watersheds, but all of the water in Adams County ultimately flows into the Chesapeake Bay.

• View local water quality on PA DEP's 2024 Integrated Report Viewer.

• View your watershed address at the River Runner website.

Adams County communities are impacted by pollution and environmental exposures and effects. The darker blue census blocks in the map below have a greater PennEnviroScreen Score due to elevated exposure/risks compared to the rest of Pennsylvania. Parameters with elevated risk/exposure (>50th percentile in PA) in Adams County include:

• Particulate matter 2.5

• Traffic

• Flood risk

• Impaired streams

Pennsylvania’s climate type is continental with distinct seasonal changes. The average high temperature in January is 40°F and 85°F in July. Average annual precipitation ranges from 42-46” with higher amounts in the western and northern parts of the county. Heat waves, flooding, and shifting seasons are predicted to be the major climate hazards in Adams County within the next 50 years. The graph below depicts measured and predicted extreme heat days with temperatures exceeding 95°F (MARISA, 2022). According to 1st Street, a resource for climate risk financial modeling, Adams County is at major risk for heat and moderate risk for flooding, fires, and winds due to severe storms.