EasyJet has said it expects to make a loss before tax of £275 million in the first half of the financial year.
Revenue is expected to grow 7.3% to £2.34 billion in the six months to March 31.
But costs will be 18.8% higher due to higher fuel prices, enlarged capacity and an increase in cost per seat.
Chief executive Johan Lundgren said: "For the second half we are seeing softness in both the UK and Europe, which we believe comes from macroeconomic uncertainty and many unanswered questions surrounding Brexit which are together driving weaker customer demand."
