Storm Antoni is set to bring “unseasonably strong” winds and heavy rain to the UK on Saturday.
The storm, which is the first to be named by the Met Office this season, will hit the UK from late Friday night and into Saturday.
Rain and wind warnings have been issued for Northern Ireland and parts of south-west Britain respectively.
Northern Ireland will see heavy rain from the early hours of Saturday morning, while parts of Wales and south-west and coastal southern England will be blasted with heavy wind.
Met Office chief meteorologist Steve Willington said the storm will bring “potentially disruptive” weather as it moves from west to east.
He added: “Northern Ireland is likely to see some of the highest rainfall totals, with 40-60mm falling in some spots, but 20-30mm more widely.
“Away from the warning area many will still see a very wet day, especially in north Wales and north England.”
He said that the strongest winds will affect parts of south-west England and south-west Wales, with gusts reaching in excess of 60mph.
“The strongest winds will affect parts south-west England and southwest Wales where exposed coasts and high ground could see gusts in excess of 60mph,” he said.
“In these areas, gusts inland could reach 50-55mph for a time. These windy conditions will likely coincide with high tides which will present an additional challenge for coastal areas.”
The RAC’s Rod Dennis warned that Saturday is expected to be the worst day on the roads of the summer so far.
“We expect Saturday to be the worst day on the roads of the summer so far, especially for anyone in the south-west of England – and that’s a lot of people as our research shows it’s the most popular part of the country for leisure trips by car this year,” he said.
“Conditions will be atrocious with a wholly unpleasant mix of very strong winds and locally intense rainfall. The best advice is to slow down significantly to stay safe and avoid exposed moorland and coastal routes until the storm passes.
“Drivers towing caravans and trailers need to be particularly careful in these conditions and those with boxes and bikes on the roof should double-check they’re secured properly.
“Drivers should also watch out for fallen trees and be prepared for the disruption they cause.”
He added that the RAC estimates that around four million cars will be suing the roads for leisure journeys across the whole weekend.
The weather has also forced organisers of outdoor events scheduled to take place this weekend to cancel their plans.
Eliot Walker, organiser of the annual Dorset jazz festival, Stompin’ on the Quomps, said he was “disappointed” he had to postpone this year’s event due to Storm Antoni. The free festival in Christchurch Quay was forced to cancel its activities for the first time in its 30-year history.
Mr Walker, 44, said: “We’re really disappointed that the town can’t come together to enjoy a wonderful day listening to professional jazz and big bands by the side of the river on the picturesque quay.”
Around 10,000 people had been expected to attend on Saturday. The decision to cancel the festival was driven by concerns for the safety of traders and spectators, as gusts of up to 60mph are predicted.
Mr Walker added: “We always keep an eye on the weather for the months leading up to the events just to get a general idea, and the closer we get, the more accurate and consistent the weather forecasts tend to be.
“But on Wednesday, we were still seeing gusts of wind to 47mph, which is quite extreme for Christchurch. And it was at that point we wanted to give our traders and bands enough time to know that they weren’t going to be performing.
“Christchurch Quay is a popular location for events. We are talking to Christchurch Town Council and trying to find available dates in either August or September to move the festival to.”
