Scotland, northern and western England are in the firing line for the assault with up to a month’s rain set to drench the region in matter of hours.
Post-tropical storm Ernesto is currently being steered towards the UK by a low-pressure system hurtling across the Atlantic.
It will drag a plume of hot, humid air into the country pushing temperatures towards 30C (86F) over the next few days.
The United States’ National Hurricane Centre estimates Ernesto will make landfall with Ireland this afternoon before unleashing its death throes across Britain at around 8pm.
In a statement this morning a spokesman said: “The post-tropical cyclone or its remnants are expected to spread gusty winds and locally heavy rain over portions of Ireland and the United Kingdom tonight and early Sunday.
“[It] is moving toward the east-northeast near 35 mph and this motion is expected to continue for the next 12 to 24 hours.