This appears to be the most serious storm in Latvia since 2005 in terms of its overall impact, says Andris Viksna at the Latvian Meteorological Centre.
The storm, with strong winds and torrential rain, began on Saturday and continued overnight into Sunday.
One person died in the city of Jelgava in central Latvia when part of a building collapsed. Wind speeds exceeded 30 metres per second, which is considered a storm, on Saturday in the capital, Riga.
More than a quarter of a million Latvians have been left without electricity, and disruptions are being reported in train, road and air traffic.
One person has died in Lithuania after being hit by a falling tree. More than 200,000 Lithuanians were without power on Sunday.
