The subtropical storm recently formed over the north Atlantic and is set to reach Ireland on Saturday evening.
In the meantime, spells of wet and windy weather are expected in Northern Ireland and along western coasts of Scotland, Wales and England on Friday.
It is set to arrive on the United Kingdom in the early hours of Sunday morning, but will only hit certain areas.
According to the Met Office, Storm Ernesto will no longer be classified as a storm when it arrives in the United Kingdom, as it is expected to have lost some of its power by the time it reaches the country, but it will still bring with it heavy rain and strong winds.
The Met Office's United Kingdom forecast states that "the north will be windy, with patchy rain" tomorrow, but "further south, winds will be much lighter, with a fair amount of warm sunshine, though patchy rain may affect western hills".
This will then turn heavier and more persistent through the afternoon, with a maximum temperature of around 20 °C.
When will rain hit Yorkshire this week?The developing hurricane is forecast to move west of 140º west into the Central Pacific by Sunday morning.
The Met Office forecast for next Thursday reads: "There will probably be a good deal of dry, bright or sunny weather, especially in the south, while the far west and northwest will have some thicker cloud and rain at times".
Gusts will peak at 40mph around the United Kingdom late on Saturday and during the early hours of Sunday morning when the storm arrives over the UK. We will see winds pick up and some heavy rain overnight Saturday into Sunday, and then it will cross its way eastwards, most likely across some parts of Scotland...