Rough seas pound against the harbour wall at Porthcawl, Wales. Photograph: Ben Birchall/PA

As Dennis rages in a week after Ciara, flights are cancelled and trains are delayed amid warnings of widespread flooding

Storm Dennis has wreaked havoc on Britain, forcing the cancellation of hundreds of flights and trains, and the deaths of at least two people yesterday.

As the so-called bomb cyclone battered the coastline, as much as a month’s worth of rainfall was predicted overnight and into Sunday morning in some parts of the UK.

By late on Saturday night there were 104 active flood warnings in England and Wales urging people to take immediate action, with another 369 flood alerts. The Met Office has issued eight weather warnings covering most of the UK for this weekend, with hundreds of homes and businesses at risk of flooding.

The worst effects were felt at sea, with two bodies pulled from the waters off the Kent coast. One man was found off Herne Bay and declared dead at the scene, while another lost his life after falling from an oil tanker. His body was found near Margate.

Other parts of the coastline were battered by winds reaching 87mph. Coastal roads in Anglesey flooded, ferry services were cancelled from Portsmouth, Poole, Plymouth and across the Solent, while Brighton town hall was opened to rough sleepers on Saturday night.

Inland, many parts of the country had been recovering from Storm Ciara last weekend, which flooded 800 homes and left half a million people without electricity. The latest assault by the weather was forcing clean-up operations to stop. Energy firms were battling to restore power to dozens of areas. At 11pm last night, Britain’s six power networks were reporting power cuts in 299 areas, with 107 in Scotland.

Families trying to leave the UK for half-term holidays also faced disruption, with flights cancelled from Edinburgh, Glasgow, Newcastle, Southend, Stansted, Heathrow and Gatwick. Easyjet cancelled 234 flights on Saturday and British Airways stopped another 40 on its routes through Heathrow, with another 100 affected at Gatwick.

EasyJet has cancelled more than 60 flights due to depart on Sunday, most on its route to Geneva, as well as to Spain, Portugal and the Canary Islands. For many passengers, the misery was compounded by their inability to book seats on replacement flights.

An easyJet spokesman said: “We are doing everything possible to minimise the impact of the disruption for our customers and to arrange alternative travel. Customers on cancelled flights have been given the option of transferring their flight free of charge or receiving a refund. We will also provide hotel rooms and meals for customers who require them.”

Flooding was already affecting some areas on Saturday. In Kendal, Cumbria, roads were impassable and railway tracks were flooded near Newquay, Manchester, Crewe, Kerne, Ebbw Vale, Windermere, Barrow in Furness and Carlisle, with several other line closures due to fallen trees.

Soldiers from the Highlanders, 4th Battalion, the Royal Regiment of Scotland in Mytholmroyd assisting with flood defences, in the Upper Calder Valley in West Yorkshire. Photograph: Danny Lawson/PA

On Saturday, 75 soldiers and 70 reservists were sent to West Yorkshire to support the recovery and bolster preparations for the incoming storm. The Environment Agency predicted flooding would be worse than last weekend, as the ground is already saturated.

As rain lashed down in Calderdale, Sourena Jowkar hunkered down at home. His business, Leila’s Kitchen, had only been open for four months in Hebden Bridge when it was crippled by Storm Ciara last weekend. On Saturday he feared another blast of bad weather, courtesy this time of Storm Dennis, would wreak yet more havoc on his livelihood.

“When we received the first flood warning [last weekend], my wife and I came to the cafe, I sat down and had a cup of tea, but things happened so quickly,” he said. “Within 30 minutes the whole cellar was flooded and we had to leave because it wasn’t safe. All my stock, the fridge freezers, the oven, everything was floating in the cellar and it was all destroyed. We only just started establishing ourselves as a business. It’s devastating.”

Across Yorkshire, which gets on average 51-67mm of rainfall in February, forecasters predicted there would be up to 80mm of rain in 48 hours. In Mytholmroyd, West Yorkshire, temporary barriers were installed in place of delayed £30m flood defences – which remain under construction.

“People are furious,” said resident Adelle Stripe, a writer. “We’ve had three serious floods in eight years; what is happening here is evidence that climate change is real. We’re not moaning or complaining, we’re pointing out that it’s real – but, on top of that, we are dealing with major human errors. The Environment Agency knew the storm was coming and didn’t fill the hole in the flood wall – the water destroyed the bottom of the village.”

Flood defences are prepared in Mytholmroyd, in the Upper Calder Valley in West Yorkshire. Photograph: Danny Lawson/PA

The problems in Mytholmroyd were compounded, said Stripe, by a steep path on the valley which had repeatedly been resurfaced with hardcore. “It’s supposed to be cobbled so the water bounces off it; instead, the hardcore washes away and so you have rubble and water rushing down and blocking all the drains, coming up the drain holes and spouting out.”Over in neighbouring Hebden Bridge, pubs and cafes battened down the hatches at 2pm. Gill Partridge, owner of Watergate Tea Rooms, said she had only had one customer and was wary of the worst ahead. “We are insured but the excess is very high and you have to suffer financially before you can trigger it,” she said.

The onus was on business owners to adapt to flood risks off their own bat, she said. “We opened this business six years ago and bought the building because it had never flooded before. We have a step of about eight inches and water would lap but it never came in. That was confounded by the 2015 floods, of course. We no longer have a cellar – it was useless, it would flood every time – so we filled it with 70 tonnes of cement. It took us two years to get business back to how it was before those floods. If this inclement weather continues, we will continue to suffer.”

Calderdale council said all its teams were working hard ahead of the next storm, and six community “flood hubs” set up last week would remain open. Local councillor Scott Archer Patient said the impact of the storms over the two weekends “could not be quantified just by the number of business closures and flooded homes”, as residents navigated between recovery and preparation. “Losing possessions and having your life turned upside down is one thing,” he said, “but there’s also a lot of anxiety here as soon as there is heavy rain. There are scars left on people: it is traumatic.”

For many families across the UK, the great half-term getaway never really happened, with flights grounded for safety reasons and train routes disrupted.

British Airways and easyJet both cancelled flights, while several sporting fixtures were also called off due to the weather. Ryanair said all of its flights were operating as normal.

A spokeswoman for Heathrow Airport said: “To minimise the number of flights cancelled at short notice we have taken the joint decision, alongside our airline and air traffic partners, to pre-emptively consolidate today’s schedule.”

Some trains were also cancelled or delayed due to flooding or fallen trees blocking the tracks.

Rail replacement buses were offered on some routes, while National Rail put speed restrictions in place on certain lines for passenger safety. It urged people to check for updates before they began any travel.