Londoners have been warned to “stay alert” as Storm Eunice batters the country with torrential rain and 90mph winds on Friday.
Train travellers have been urged to rethink journeys amid warnings that strong winds could cause trees to be blown on to train lines, leading to delays and cancellations.
The Met Office have issued a rare red weather warning from 7am on Thursday to 12am on Friday for the coastline of Devon, Cornwall and Somerset as well as the south coast of Wales.
It means damage to homes, train cancellations and power cuts are likely and people in affected areas should stay at home.
A lower amber weather warning is also in place covering the rest of Wales and much of England as far north as Manchester and Hull while a yellow warning covers Northern Ireland and much of Scotland.
The UKHSA London account tweeted: “#StormEunice is expected to bring very strong winds on Friday.
“Be alert – listen for weather warnings and secure loose items in your garden or on balconies.
“If you must travel, take extra care as strong winds could knock down trees and pick up debris.”
Met Office forecaster Becky Mitchell said the UK had only seen a “handful of storms in the past 30 years” that had brought similar gusts.
She told the Mirror: “It’s got the potential to be up there as quite a notable storm. Winds are likely to be 60 to 70mph inland across the south of the UK. It’s quite unusual, we don’t see gusts that high over such a wide area in the south.”
A spokesperson for the weather agency said: “People in the red warning area are advised not to go out unless it’s absolutely essential. Gusts of wind could create flying debris and waves could cause flooding along coastal areas.
“The last time we issued a red warning was in the autumn for Storm Arwen. We’re going to see wind, rain and snow.”
Paul Gundersen, the Met Office’s meteorologist, said the storm was caused by an active jet stream that is “driving low-pressure systems across the country.”
Forecaster Met Desk said: “Storm Eunice looks absolutely brutal on Friday, a very dangerous, damaging storm.
“These type of wind gusts across South Britain are very rare. Flying debris and falling trees will be a huge problem.”
A Network Rail spokesman said disruption is “inevitable” and there will be blanket speed restrictions of 50mph in most places, with winds forecast to reach 90mph in some areas.
South Western Railway said a speed restriction will be in place across its entire network for most of Friday.
And TransPennine Express urged people not to take the train on Friday amid severe weather expected in northern England and Scotland.
Paul Watson, operations director for the firm, said: “Storm Eunice will be the second storm to impact our services this week and it is likely to cause major disruption to train services, right across the North of England and into Scotland.”
Avanti West Coast said it will run an amended timetable on Friday, with longer journey times due to speed restrictions.