Menard County is a county in the U.S. state of Illinois. According to the 2010 United States Census, it had a population of 12,705. Its county seat is Petersburg. Menard County is part of the Springfield, Illinois, IL Metropolitan Statistical Area.
Menard County at the time of its creation in 1839
Menard County in 1841, reduced to its present borders
According to the US Census Bureau, the county has an area of 315 square miles (820 km2), of which 314 square miles (810 km2) is land and 1.0 square mile (2.6 km2) (0.3%) is water.
In recent years, average temperatures in the county seat of Petersburg have ranged from a low of 17 °F (−8 °C) in January to a high of 87 °F (31 °C) in July, although a record low of −24 °F (−31 °C) was recorded in February 1905 and a record high of 112 °F (44 °C) was recorded in July 1954. Average monthly precipitation ranged from 1.62 inches (41 mm) in January to 4.06 inches (103 mm) in May.