Nisa is a municipality in Portalegre District in Portugal. The population in 2011 was 7,450, in an area of 575.68 km². The present Mayor is Mariā¦Nisa is a municipality in Portalegre District in Portugal. The population in 2011 was 7,450, in an area of 575.68 km². The present Mayor is Maria Idalina Alves Trindade. The municipal holiday is Easter Monday.