Goretti, the first named storm of the year, received its name from the French meteorology service.
The storm is likely to undergo “explosive cyclogenesis” or “weather bomb”, which is where central pressure drops to create powerful gusts over a few hours.
The strongest winds are forecast for parts of Cornwall and the Isles of Scilly.
The Met Office said winds would strengthen through Thursday afternoon then “gradually ease from the west through the early hours of Friday”.
It advised people to secure loose items outside their homes and to check road conditions and public transport timetables for potential travel disruption.