The name Stenungsund comes from the village stenunge that was located where central Stenungsund now exists. Historians believe the name meant "the village at the foot of the mountain." The village had several names including Staenungum, Steffningsbyn and lastly Stännung. On 23 September 2023 a
quick clay landslide on the
E6 highway took place, injuring three people and destroying the motorway, a local road, a fuel station and a fastfood restaurant. A shop selling wood and building materials lost its access to the road network. After nine months of repair work, the E6 motorway reopened on Friday the 5th of July 2024, in the early morning hours. ==Climate==