Flights will be grounded on Saturday for safety reasons as winds are forecast to reach 70mph along coastlines, while some parts of the country could get up to 4.7 inches of rain.
EasyJet has cancelled over 230 flights in and out of the UK on Saturday.
A spokeswoman for easyJet said: “Due to forecasted adverse weather conditions caused by Storm Dennis, easyJet, like other airlines, is currently seeing disruption to its flight programme for Saturday February 15th.
“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.
British Airways has also confirmed cancellations, and a spokesman for the airline said: “The majority of our flights are planned to operate as planned, but, like all airines flying to and from the UK today, we are experiencing some disruption due to the stormy weather conditions.
“We are merging a small number of Heathrow short-haul flights to the same destination and using larger aircraft where possible to minimise disruption.”