An ‘amber’ weather warning has been issued, with forecasters saying the storm may develop over south west England early on Friday, before spreading north and east during the day.
While there is still some uncertainty in the track of Eunice, there is an increasing likelihood of widespread inland wind gusts of 60-70 mph and up to 80 mph in a few places.
The ‘extremely strong winds’ may cause significant disruption.
Around coasts of west Wales and southwest England, gusts of 90 or possibly even 100 mph are possible.
Winds are expected to ease across western areas through the afternoon, and eastern areas during the evening.
Forecasters say there is a good chance that flying debris could result in a danger to life. Damage to buildings and homes is likely, with roofs blown off and power lines brought down.
Roads, bridges and railway lines are likely to close, with delays and cancellations to bus, train, ferry services and flights.
Forecasters add there is a good chance that power cuts, possibly prolonged, could occur and possibly affect other services, such as mobile phone coverage.
Large waves are likely and beach material is likely to be thrown onto sea fronts, coastal roads and properties. It is likely there will be falling branches and some uprooted trees.