The flooding, caused by heavy rains last week, pushed Polish rivers to their highest levels in more than 100 years and caused an estimated $576 million in damage, Sky News reported Wednesday.
Weather forecasters said rain and storms would affect Poland until the middle of the week, increasing the risk of flooding in Germany as the systems push north along the Vistula and Oder rivers.
About 4,000 people have been evacuated along the Vistula's path, northwest of Warsaw, the British news outlet said.
In eastern Germany, where the Oder River runs along the German-Polish border, water levels have started to rise, prompting flood warnings in Ratzdorf and Eisenhuttenstadt, officials said.
Polish Prime Minister Donald Tusk has pledged more than $576 million in aid for the tens of thousands of people left homeless in southern and central Poland because of the flood. Tusk said the funds would come from a Polish government reserve meant to co-finance European Union projects.