With the Met Office issuing an amber weather warning until 6pm on Saturday 13 October, passengers on planes, ferries and trains are experiencing severe disruption.
The area affected by the amber warning is South Wales, Gloucestershire and Somerset, with a “good chance” that some communities will be cut off by flooded roads.
The Met Office warned that Storm Callum will bring “heavy rain during Friday and continuing into Saturday – particularly over south facing hills”.
A more extensive yellow warning of strong winds is in place across the west of the entire UK: Cornwall and Devon, the western half of Wales, parts of Cumbria, western Scotland from the Mull of Kintyre to Cape Wrath, all the Hebrides and all of Northern Ireland.
Dozens of flights have been cancelled. At George Best Belfast City Airport, the entire first wave of Flybe flights has been cancelled. Other flights are operating with delays.
Loganair, which serves the Western Isles of Scotland, is offering passengers booked on Friday 12 October to defer their trip by up to a week to avoid the risk of disruption.
“We are continuing to plan to fly all our scheduled services, and we have standby aircraft and crews in place to help recover any disrupted services,” the airline said.
Many flights to and from Cardiff and Newquay have been cancelled, and KLM cancelled its morning flight between Bristol and Amsterdam.
Even though Britain’s busiest airport is outside the yellow warning area, Eurocontrol tweeted: “Strong winds affecting London Heathrow.”
At least a dozen flights to and from Heathrow have been grounded, including Aer Lingus to Dublin, Lufthansa to Munich, SAS to Copenhagen and British Airways to Madrid.
At Gatwick, links with Newquay on Flybe and Dublin on Aer Lingus have been grounded.
Caledonian MacBrayne, which operates ferries in the Hebrides, has cancelled services on most routes.
On the railways, Arrive Trains Wales warned: “Severe weather is forecast to affect the Wales & Borders area through this coming weekend. Severe flooding caused by extreme rainfall and coastal flooding is forecast.”
All trains between Swansea and Carmarthen before 11am and after 7pm have been cancelled “due to anticipated coastal flooding caused by strong winds coinciding with high tides”.
“Very limited replacement buses will be in operation and customers are advised to avoid travelling,” said the train operator.
Similar problems are expected on the mainline from London Paddington to Penzance via Exeter and Plymouth. GWR trains are running at reduced speeds, while CrossCountry services will not operate along the South Devon coast until after the morning high tide passes at 11am “owing to waves predicted to be overtopping the exposed sea wall at Dawlish”.
Due to predicted tidal flooding between Liskeard and Looe, all train services on this Cornish branch line have been suspended on Friday and Saturday.
No trains will run on the main east coast line in Scotland between Aberdeen and Dundee due to a derailed train at Stonehaven.
“We anticipate the line will reopen by 3pm,” said Scotrail.