July – The flood Storofsen struck eastern Norway.[2]
9 July – Theater War part of the Russo-Swedish War (1788–1790): Denmark-Norway agreed to cease active engagement in the conflict. A statement of neutrality was issued by Denmark-Norway, not a formal peace treaty and Denmark-Norway leaves the war.
12 November – The Norwegian army retreated from Bohuslen back to Norway. During the retreat, the Norwegian army lost 1,500-3,000 men to hunger, disease, poor sanitary conditions, and exposure to continual autumn rainfall