A tropical storm heading along the US east coast could move across the Atlantic, threatening a dramatic break in the UK's sizzling summer weather.
Hurricane Bertha, which has now been downgraded to a tropical storm, is expected to weaken as it heads towards Europe.
But its winds of around 75 miles per hour have already caused destruction in Puerto Rico and the Bahamas.
"We won't be seeing a 'hurricane in Europe', but there is a chance we could see a fairly active summer storm," said the Met Office in a blog.
It adds: "While all forecast models suggest the storm will head in the general direction of UK and continental Europe, there remains a lot of uncertainty about exactly what it will do."
Meteorologists are currently studying forecast models before committing themselves to a definite outcome.
Sky News weather presenter Isobel Lang said: "The Sky News Weather Team will be watching the track of this ex-hurricane very closely as it crosses the Atlantic.
"The details are sure to change but the general picture through Sunday and into Monday is for a period of rain and strong winds with the risk of gales.
"With RideLondon and other events taking place, it's worth keeping up to date with our catch-up service."
The RideLondon event will see elite riders take to the streets on Saturday, and on Sunday around 24,000 amateur cyclists will ride through London and Surrey on a similar route to that of the London 2012 Olympic Road Cycling Races.
The weekend also sees an number of music festivals around the country including Fairport's Cropredy Convention in Oxfordshire, Strawberry Fields Festival in Leicestershire and Bath Folk Festival.
Lang adds: "Once the storm clears the weather looks set to turn rather autumnal and showery."
It looks likely that the earliest Bertha would affect the UK would be on Sunday or into the start of next week.
The Met Office said it will be keeping an eye on how this situation develops over the next few days "to give everyone in the UK the best advice on what Bertha is likely to do".
It said: "Given the time of year and the potential heavy rain, strong winds and large waves Bertha could bring if it does head to the UK, we'd advise everyone to stay up to date with the latest forecasts and warnings from the Met Office over the next few days."
