Webb is a city in Clay County, Iowa, United States. The population was 138 in the 2020 census, a decline from 165 in 2000. The Webb post …Webb is a city in Clay County, Iowa, United States. The population was 138 in the 2020 census, a decline from 165 in 2000. The Webb post office opened in 1900. Webb's longitude and latitude coordinatesin decimal form are 42.948134, -95.012281.