sentences:  In recent years, average temperatures in the county seat of Eureka have ranged from a low of in January to a high of in July, although a record low of was recorded in February 1905 and a record high of was recorded in July 1936.Average monthly precipitation ranged from in January to in May.As of the 2010 United States Census, there were 38,664 people, 14,276 households, and 10,675 families residing in the county.