From November 26 to December 4, "public activities and shows will cease, the national flag will fly at half mast on public buildings and military installations," a statement from the state executive said.
Castro's ashes will be buried in the historic southeastern city of Santiago on December 4 after a four-day procession through the country, it added.
President Raul Castro earlier said that his older brother Fidel was to be cremated early today.