Parts of England and Wales are being battered by high winds as the south of the UK braces for the full impact of what forecasters say could be one of the most powerful storms to hit in years.
With wind speeds reaching 140 kilometres an hour, the storm has been dubbed St Jude, after the patron saint of lost causes who is traditionally celebrated on October 28.
The winds are expected to peak during Monday's morning rush hour, causing possible disruptions for millions of commuters.
Two rail companies have already cancelled morning rush-hour trains, with further disruption expected for roads and airports.
Residents have also been told to prepare for widespread floods, blackouts and damage.
Comparisons are being drawn with 1987, when a storm killed 18 people in Britain and felled 15 million trees.
Prime minister David Cameron chaired a meeting between the Environment Agency, forecasters and government departments on Sunday to discuss contingency plans for the impact of the storm.
Emergency planning began last week
Britain's rail network operator said a revised timetable was already being put in place on some routes, while the Highways Agency warned road bridges may need to be closed.
London's main Heathrow Airport said it was expecting delays and cancellations.
"The thing that's unusual about this one is that most of our storms develop out over the Atlantic so that they've done all their strengthening and deepening by the time they reach us," Met Office spokeswoman Helen Chivers said.
"This one is developing as it crosses the UK, which is why it brings the potential for significant disruption ... and that doesn't happen very often."
The Met Office said advances in forecasting technology had enabled it to predict Monday's storm well in advance, and that it had started discussions with local councils, emergency services and transport operators early last week.
Last year a storm with winds of up to 130kph hit parts of Scotland, in what the Met Office said was Britain's most severe storm since 1998.