At least one person was killed, swept away in a bloated stream, police said.
Roads remained closed Friday after storms dropped up to an inch of rain an hour.
The deluge triggered slides and knocked down trees. At one point, the Met Office recorded more than 1,000 lightning strikes in a 5-minute period, The Daily Telegraph said.
A 66-year-old retired math teacher who was forced to abandon his car died Thursday after he lost his footing and was swept away in a stream near his home in Bitterley, England, The Sun reported.
East Coast train service was canceled Friday between Newcastle and Edinburgh because of flooding and a landslide near Berwick-upon-Tweed, the Telegraph said.
More than 15,000 homes were without electricity in Northern England and the Midlands and more than 10,000 homes in the Irish Republic and 1,000 in Northern Ireland were affected by power outages.
The torrential rains and flooding added to the misery of what has become one of the wettest Junes in the history of weather record-keeping in Great Britain. More than 1,000 homes and businesses were flooded last weekend when an estimated month's rain fell in a single day in some places.
More bad weather was forecast in parts of western Britain.