Storm Hannah is set to bring strong winds and much cooler conditions to the UK, with temperatures expected to plunge more than 10 degrees in some parts.
Gusts of up to 75mph are forecast to hit the south-west coast by Friday evening.
Heavy rain and strong winds throughout Saturday are likely to make conditions feel colder, the Met Office said, as temperatures drop into the low teens, slightly below the average for the time of year.
Storm Hannah, which was named by Irish forecaster Met Eireann, will bring gusts of up to 80mph to the south-west coast of Ireland on Friday afternoon, before moving towards Wales and the south west of England.
Highs of just 12C or 13C will be in stark contrast to the balmy weekend just passed, which saw highs of 25C recorded in London and the warmest Easter Monday on record in the UK and Ireland.
Met Office meteorologist Greg Dewhurst said: “When you add on the strength of the wind and the rain it will feel colder.”
The Met Office has a yellow weather warning in place for the south west of the country from Friday night until Saturday afternoon.
Storm Hannah is expected to clear the UK by Sunday, meaning decent weather for those taking part in the London Marathon, and more settled conditions are forecast to return next week.
Met Office chief forecaster Frank Saunders said: “We’re going to see an unsettled period over the next few days, but the forecast for later next week indicates the return of high pressure, bringing more settled conditions.
“Storm Hannah will move away from the UK during Saturday followed by a transient ridge of high pressure bringing more settled weather to the UK for Sunday, good news for London Marathon runners.”