The tropical storm was named a hurricane overnight and the US National Hurricane Centre has warned it could strengthen over the coming days.
The remnants of Ophelia look set to reach the UK on Monday, with unsettled weather expected to cause disruption, the Met Office said.
The west of the country will see the worst of the weather, with winds of between 60mph and 70mph forecast.
It will coincide with the 30th anniversary of the Great Storm of 1987, which hit southern England overnight on October 15.
The storm caused damage estimated at £1 billion and claimed 18 lives.
Met Office forecaster Alex Burkhill said: "Ophelia became a hurricane overnight and the forecast track takes it eastwards towards Iberia for the weekend.
"After that, indications are that by that point it will then have weakened and be no longer a hurricane or tropical storm, it will be extratropical.
"But then it will continue its way towards the British Isles, probably reaching us very early next week."
Mr Burkhill said cold sea temperatures mean Ophelia will not be strong enough to be categorised as a hurricane when it hits Britain.
But he added: "It's definitely something that we are keeping an eye on, for the possibility of some disruptive weather early next week."
The unsettled weather looks likely to continue into Tuesday due to a separate band of low pressure, and will remain changeable throughout the rest of the week.