The Town of Harrisburg lies in the Piedmont region of the State of North Carolina, which is the middle region of the state, located between the Coastal Plain and the Mountain regions. Piedmont is a French word meaning "foot of the mountain." The elevations of this region range from about 300 feet in the western Coastal Plain to about 1,500 feet near the mountains, with the Town of Harrisburg having elevations ranging from 500 feet to 600 feet. The boundary between the Coastal Plain and the Piedmont is called the fall line or fall zone. Along this area, rivers flow from the older, harder rocks of the Piedmont to the softer rocks of the coastal Plain. Along the fall line, rivers form shoals, low waterfalls, and rapids. Below the fall line, streams are usually sluggish and smooth-flowing. Above the fall line, where the Town of Harrisburg sits, the streams are rocky and shallow, making boating difficult.
Harrisburg, much like most of North Carolina, has a humid, subtropical climate. Winters are short and mild, while summers are usually very sultry; spring and fall are distinct and refreshing periods of transition. Temperatures rarely go above 100°F (38°C) or fall below 10°F (–12°C), but differences in altitude and proximity to the ocean create significant local variations. Average January temperatures range from 36°F (21°C) to 48°F (9°C), with an average daily maximum January temperature of 51°F (11°C) and minimum of 29°F (–2°C). Average July temperatures range from 68°F (20°C) to 80°F (27°C), with an average daily high of 87°F (31°C) and a low of 66°F (19°C). Average yearly rainfall for Harrisburg is 43.8 inches, consistent with the average rainfall for Cabarrus County.