The high winds and heavy rain brought from the Atlantic by Storm Brendan are seriously disrupting travel – with air-traffic control strikes also causing problems.
Many Western Isles ferries have been cancelled for the day in Scotland by Caledonian MacBrayne.
On the Irish Sea, many sailings are disrupted because of the high winds.
On the railways, the main problems are speed restrictions imposed as safety precautions. Trains on the line through Anglesey between Holyhead and Bangor will travel more slowly until 6pm.
In Devon and Cornwall, a speed restriction has been imposed between Exeter and Penzance that will add 20 minutes to journeys until 9pm at the earliest.
At the world’s busiest single-runway airport, Gatwick, bad weather triggered the diversion of numerous flights on Monday night.
Wizz Air’s flight from Bucharest ended up in Birmingham, and the Gdansk arrival touched down in Stansted.
Meanwhile easyJet diverted a flight from Turin to Birmingham and another from Athens to East Midlands.
Passengers were either flown to Gatwick later in the evening, or put on coaches.
A strike by Italian air-traffic controllers has hit British Airways passengers between London, Italy, Switzerland and France.
British Airways has cancelled three round-trips from Heathrow to Milan, as well as links to Rome and Nice.
From Gatwick, BA has axed flights to Rome and Venice, and their return journeys.
Alitalia, easyJet and Ryanair have also cancelled dozens of domestic flights within Italy.