The Ministry of Defence has placed 800 personnel at higher readiness as Storm Eunice continues.
The death of a man in County Wexford was confirmed by police in Ireland, while a member of the public is in hospital with serious injuries after being struck by falling debris from a roof in Henley-on-Thames, Thames Valley Police said.
Millions of people have been urged to stay at home for the day due to safety fears over the impact of Eunice, one of the worst storms to hit the UK in a generation.
London Ambulance Service said two people were taken to hospital after being struck by falling debris and a tree in separate incidents in Waterloo and Streatham.
Tens of thousands of homes have been left without power, while flights, trains and ferry services have been suspended, and roads, schools and businesses have shut as potentially record-breaking gusts of more than 120mph have been recorded in some areas.
The Met Office issued "red" weather warnings for Friday, which means danger to life is expected, with more weather warnings issued for Saturday.
A separate amber weather warning is also in place for gusts across England until 21:00, as well as yellow warnings for snow in Scotland and Northern Ireland.
The Met Office has issued a less-severe yellow wind warning for much of the south coast of England and South Wales on Saturday, which it said "could hamper recovery efforts from Storm Eunice".