The Met Office has issued a series of weather warnings stretching from the north-west coast of Scotland to Land's End, including Northern Ireland, while a number of flood warnings and alerts are in force across south-west England and south Wales.
Storm Callum is now swirling off the southwest coast and will deepen rapidly over the course of the next 12 hours, according to Midland weather expert Cathal Nolan.
The Met Office issued an amber warning across much of south Wales, advising residents to expect torrential rain and widespread disruption to travel from Friday morning until Saturday evening.
While on Saturday there is a "danger to life" alert over potential flooding due to rain covering Lothian and Borders and Dumfries and Galloway.
There is a chance that homes and businesses could be flooded, causing damage to some buildings.
The storm has brought very strong winds and heavy rain in many places, with the western side of the country experiencing some of the strongest winds.
Some areas of Wales and parts of Scotland could get a further 50mm to 80mm of rain on Saturday.
Meanwhile winds of 50 to 60mph are expected widely in warning area, with gusts expected to peak at 70mph in the most exposed parts.
Winds of up to 60 miles per hour are expected to hit the area, which combined with high tides could lead to some coastal impact due to large waves.
Train cancellations will affect those travelling the Shrewsbury to Aberyswyth line through Mid Wales all weekend.
"There is a deep area of low pressure to the west of Ireland, and it will bring strengthening winds to Ireland as well as western parts of the British Isles".
If flooding does occur there is a chance that trains or bus services could be cancelled.
"The rain is expected to be accompanied by strong winds, which when combined with high tides may lead to some coastal impacts due to large waves", Met office forecasters said last night.