1940 (MCMXL) was a leap year that began on a Monday in the Gregorian calendar.
The city of Karlskoga receives a city privilege.
The film The Wizard of Oz with Judy Garland has a Swedish premiere.
100,000 Swedes work weekends in 400 Swedish companies and donate the income to Finnish Aid under the motto "Thirteenth day for Finland".
Sweden's first ski lift is inaugurated in Åre.
January 8 - The Swedish Parliament approves the introduction of coercive measures in wartime.
January 10 - An operational Swedish air force is transferred to Kemi in Finland.
January 12 - Aircraft from the Soviet Union bomb cities in Finland.
January 15 - Some censorship of postcards is introduced in Sweden.
January 16 - The first Finnish children of war arrive in Haparanda and are then taken on to host families around Sweden, where they will live until conditions in Finland return to normal.
January 17 - Swedish Foreign Minister Christian Günther comments on the conflict between Finland and the Soviet Union by claiming "Finland's cause is ours".
January 18 - Sandeman's patisserie on Östra storgatan 36 in eastern Jönköping, Sweden is on fire.
January 20 - Europe is hit by a cold wave in which the Thames freezes to ice for the first time since 1890 and snow falls on the Riviera.
January 26 - The National Information Board is established in Sweden with the task of monitoring Swedish books, the press, radio and film, among other things.
January 27 - The Amiralen Cinema Theater in Malmö is inaugurated by Jens Edvard Kock.
January 29 - Freedom of the press and information in Sweden is restricted when mainly communist newspapers and anti-Nazi After all! gets a transport ban.
January - The Swedish government grants SEK 23.5 million for the construction of fortifications along the Scanian coast, the so-called Per Albin line.
February 1 - Soviet offensive off Karelia and Ladoga.
February 3 - The first "battle group" of Swedes ends up in fighting in the Finnish Winter War.
February 10 - During the anti-communist atmosphere in Sweden, the Swedish police raid communist premises and newspaper editorial offices on government directives.
February 16 - The German freighter Altmark is boarded by the English in the so-called Altmark store.
February 21 - Soviet aircraft accidentally bomb Pajala. Houses and farms in the village meet, but no one is killed or seriously injured.
February 24 - The Swedish National Board of Health and Welfare is given the right to order the placement of unwanted foreigners in care.
March 2 - Both Swedish and Norwegian governments say no to the transit of Allied troops through the countries to Finland.
The Soviet army takes over Viborg.
The communist newspaper Norrskensflammans hus in Luleå is destroyed after a fire. Five people die ..
March 4 - In Sweden, a so-called "cooking holiday" is introduced in schools to save on the heating of classrooms.
March 5 - Katyn massacre: Members of the Soviet Politburo (Josef Stalin, Vyacheslav Molotov, Lazar Kaganovich, Mikhail Kalinin, Kliment Voroshilov, and Lavrenty Berija) sign an order, prepared by Beria, to execute 25,700 of the Polish intelligentsia, including 14,700 Poles prisoners of war.
the 13th of March
The Finnish Winter War ends with a peace agreement in Moscow between Finland and the Soviet Union after three and a half months of war. The conditions in many parts of the world are considered very harsh for Finland. The fighting ends the next day.
The American film Ninotchka with Greta Garbo in the female lead role has a cinema premiere in Sweden and is a success.
March 21 - Sweden introduces ban on transport for communist newspapers.
Heinrich Himmler gives orders to build a concentration camp in Auschwitz.
Coffee and tea are rationed, which will be the first Swedish rations during the Second World War.
March 31 - German cruiser Atlantis leaves the Wadden Sea for what is to come