Rumpus Callum will pass to the west of Ireland, northern England and Scotland during Friday, according to the Met Help.
The main impacts on the UK will be heavy rain across some western fields on Friday and Saturday.
A Yellow Warning for rain is in place from 6am to midnight on Friday.
Stodgy slow-moving rain is expected to affect Cumbria and parts of North West England and Wales.
Some blocks of the UK could get 60mm of rain in 12 hours, whereas others may see as much as 100mm by the end of the day.
The shower should then move slowly northwards on Saturday, but a Yellow Ride out Warning will still be in place.
Some areas of Wales and divisions of Scotland could get a further 50mm to 80mm of rain on Saturday.
Sioned Warrell, Realistic Resources Wales duty tactical manager, warned flooding could crop up as a result of the rain.
UK weather: A satellite image shows rain will spread above the UK
UK weather: A map shows Callum’s path
Ms Warrell said: “The current forecasted rain could cause crowding this week, especially in south and west Wales, and we are urging people to manufacture themselves.
“Making sure you know what the situation is like where you exist is really important.
“Our teams are doing all they can to reduce the risk for communities, but if there is excessing we want to make sure people are doing all they can to keep themselves all right.”
Strongest winds have also been forecast in western Ireland, with North Western go aways of the UK expected to be hit by severe gales.
UK weather: It’s time to dig out your shields as rain is on its way
There is a wind warning in place from 3am to midnight on Friday, which bedclothes Northern Ireland and parts of Western Scotland.
Gusts of 50mph to 60mph could reach some places, with the predictability of reaching 70 mph around some coasts and hills.
There is a unexpected of gusts of 70mph to 80mph in the Western Isles during Friday afternoon and evening.
Chief Meteorologist at the Met Establishment Frank Saunders, said: “Strong winds at this time of year can improve the rate of leaf fall which can potentially block drains or culverts.
“With the forceful rainfall expected over Friday and Saturday, could well strengthen the potential for flooding.
“There is also a risk that the high alarm take risks associated with Storm Callum, combined with high tides, may broach to some coastal impacts due to large waves.”