The budget airline, which is set to report its third-quarter results on Thursday, was forced to issue a profit warning in the days after the referendum, and then signalled that it could move its headquarters to Europe.
City analysts believe that full-year profits could take a £50 million hit from a combination of slowing demand following the Brexit vote, currency and fuel price swings and disruption suffered in May and June.
Wyn Ellis, an analyst at Numis, said: “Roughly four weeks on it will be interesting to see what impact Brexit has actually had on bookings at a vital time of the year and whether there is any further change to guidance.”
Numis has downgraded its profit forecast to £612m. A consensus of City analysts puts the number lower at £592m.