The capital is set to be lashed with heavy rain and fierce winds as the tail-end of a hurricane smashes into the UK.
Tropical Storm Ophelia is set to become a hurricane before it reaches British shores on Monday, experts say.
However, the Met Office says Ophelia looks likely return to storm status while crossing the Atlantic.
A spokesman said: "Having maintained such speed so close to reaching the UK, the storm will retain a lot of energy and bring a lot of wet and windy weather with it."
Londoners are set to bask in 20C heat over the weekend before Ophelia hits the south-west next week.
Ophelia will bring gusts of up to 50mph, hitting at least 74mph as it approaches Western Europe.
It is the 14th named storm of the season and would become the 10th in a row to reach hurricane strength.
Last week, Hurricane Nate hit Central America, killing at least 22 people.
