Vestfold (pronounced [ˈvɛ̂stfɔɫ] ) is a county and a current electoral district in Norway. Located on the western shore of the Oslofjord, it borders Buskerud and Telemark counties. The county administration is located in Tønsberg, Norway's oldest city, and the largest city is Sandefjord. With the exception of the city-county of Oslo, Vestfold is the smallest county in Norway by area.
Vestfold is located west of the Oslofjord, as the name indicates. It includes many smaller, but well-known towns in Norway, such as Holmestrand, Horten, Åsgårdstrand, Tønsberg, Sandefjord, Larvik and Stavern; these towns run from Oslo in an almost constant belt of urban areas along the coast, ending in Grenland in neighbouring county Telemark. The river Numedalslågen runs through the county. Many islands are located at the coast. Vestfold is mostly dominated by lowland and is among the best agricultural areas of Norway. Winters last about three months, while pleasant summer temperatures last from May to September, with a July average high of 17 °C (63 °F).