In recent years, average temperatures in the county seat of Lacon have ranged from a low of 15 °F (−9 °C) in January to a high of 87 °F (31 °C) in July, although a record low of −27 °F (−33 °C) was recorded in January 1999 and a record high of 103 °F (39 °C) was recorded in July 2005. Average monthly precipitation ranged from 1.55 inches (39 mm) in January to 4.20 inches (107 mm) in May.
There were 5,225 households out of which 29.60% had children under the age of 18 living with them, 60.80% were married couples living together, 6.70% had a female householder with no husband present, and 28.80% were non-families. 25.00% of all households were made up of individuals and 12.60% had someone living alone who was 65 years of age or older. The average household size was 2.47 and the average family size was 2.95.
In the county the population was spread out with 23.50% under the age of 18, 7.20% from 18 to 24, 25.60% from 25 to 44, 24.90% from 45 to 64, and 18.80% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 96.00 males. For every 100 females age 18 and over, there were 94.70 males.
The median income for a household in the county was $41,576, and the median income for a family was $48,061. Males had a median income of $35,765 versus $21,452 for females. The per capita income for the county was $19,065. About 3.80% of families and 5.60% of the population were below the poverty line, including 6.90% of those under age 18 and 5.40% of those age 65 or over.