The Foreign and Commonwealth Office is advising passengers to check-in their luggage to reduce the number of bags that need screening.
EasyJet, which operates flights between the UK and Lisbon, Porto and the Algarve, said passengers should expect longer security queues until Monday due to the industrial action.
A spokesman for the Luton-based carrier said: "We have been informed that airport staff will be there to reduce any impact caused by the strike.
"However, we strongly recommend that you allow extra time for your journey through the airport to be able to get to the gate on time."
British Airways expects the departures area of Lisbon Airport to be "particularly affected" by the strike.
A BA spokeswoman said: "We intend to operate our normal schedule of flights, but you may face longer waits at the central security search area at some points on each of the days."
Travel trade organisation Abta said the Algarve is one of the most popular Easter destinations for UK holidaymakers, with temperatures set to reach 23C.