Poland has suffered storms, hail, possible tornadoes and flooding since the start of the week.

Thunderstorms followed a hot day on Monday and rain turned torrential again on Tuesday night.

A spokesman for Poland's firefighters, Pawel Fratczak, told The Associated Press news agency on Tuesday that some 20,000 households remained without electricity in central and northeastern Poland where falling trees broke power lines the previous day.

Some 70 roofs were torn off or damaged by unusually violent winds. Fallen trees blocked roads and railway tracks. Fratczak said that three firefighters were slightly hurt at three different locations.

These storms were generated as a cold front edged south through northern Europe, dropping temperatures by at least 5C. In addition, it produced heavy rain in a line from Switzerland through the Czech Republic and Poland to Belarus.

This front is still active and has brought hours of rainfall overnight to Poland. Flooded streets and metro stations in the capital, Warsaw, caused significant disruption to commuters on Wednesday morning. Some roads were covered in water several centimetres deep, and tunnels were made impassable.

To the east of Warsaw and the Vistula river, the town of Sulejow recorded a whopping 111mm of rain, most of it falling in only four hours during the night.

In southern Poland, both Krakow and Katowice caught more than 50mm of rain.

Source: Al Jazeera and agencies