The joint decision was taken by the mayor of Echternach, police and the CGDIS. The army will be deployed to aid with the operation.
Residents are asked to remain at home if possible and avoid leaving the city on their own prior to the organised operation in the afternoon.
The evacuation will only apply to residents in zones which have been severely impacted by the flooding. It is not a mandatory evacuation.
Cédric Ganzer of the Grand Ducal Fire and Rescue Corps said the emergency services did not expect the situation in Echternach to worsen, but that it would take several hours to stabilise the area.
People in the worst-hit zones will be left without power or running water for the next few hours, hence the need for evacuation.
The Trifolion cultural centre on Porte St Willibrord in Echternach has opened as a refuge for people in need of assistance.
Vianden is also being evacuated - more here.
