The power cuts affected as many as 8,000 customers on Tuesday night. The south-western coast was worst affected by the blackouts, but parts of Helsinki also lost power for a time. Energy company Fortum says falling trees interrupted power to customers.
The storm, which is part of the same weather system as Hurricane Katia, is not yet out of the ordinary for an autumn storm.
Winds gusted as strong as 23 metres per second in some sea areas, and Linda Line's fast ferry services between Helsinki and Tallinn were cancelled through Thursday morning.