A spokesman for the Met Office said: "Spells of heavy and prolonged rain are expected to affect parts of England and Wales over the weekend with a higher likelihood of impacts now expected in some areas".
British army personnel are set to provide support for stretched communities in the flood-hit Calder Valley region in West Yorkshire.
Flights from Dublin to Newquay and Paris have already been cancelled while arrivals from the Isle of Man, Newquay and Paris have also been cancelled.
"These warnings mean that extensive flooding is expected to properties and businesses with many roads impassable".
Flooded streets in Appleby-in-Westmorland, Cumbria, as Storm Ciara hits the United Kingdom on Sunday February 9, 2020.
Ronaldsway Met Office has issued a yellow warning for severe gales, coastal overtopping and heavy rain across the whole Island which is in place until 6am tomorrow.
"South to southwesterly winds will gust to 50 to 60 miles per hour along exposed coasts and over high ground".
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Storm Dennis follows just one week on from Storm Ciara, which caused travel chaos last weekend with cancelled trains, buses, and roads blocked by fallen debris.
The Met Office said the "main areas of concern" on Saturday are north and south-west England and Wales, with the South East bearing the brunt more on Sunday.
A yellow wind warning is in place for all of Scotland from 10am on Sunday until 12pm on Monday, with gusts of up to 70mph expected at times.
Meanwhile, airlines have grounded flights in anticipation of the bad weather, and further cancellations may occur at short notice when the storm moves in on Saturday.
Households living near rail lines have been asked to secure any loose gardens items, after several trampolines were blown on to the tracks last weekend.
Hundreds of flights have reportedly been delayed or canceled in the United Kingdom due to Storm Dennis.
The broadcaster announced that the decision was taken due to health and safety reasons.
Severe flood warning were issued for the Scottish Borders and for the River Neath in South Wales, while local media reported the River Taff had burst its banks at Pontypool. "The rapid response of the Army today will help with provision of flood relief to local communities in West Yorkshire".