U.K. holidaymakers reappeared with a roar, showering EasyJet Plc and tour operator TUI AG with summer bookings just hours after Prime Minister Boris Johnson outlined a roadmap for air travel to return.

EasyJet ticket sales more than quadrupled in the hours after Johnson said Monday that international trips may restart as soon as May 17, the U.K. carrier said in a statement. TUI, which offers hotel and flight packages, said holiday bookings to Spain, Turkey and Greece jumped sixfold overnight.

Airline shares advanced for a second day on mounting evidence of customer demand waiting to be unleashed over the crucial summer period. While travel could open as soon as late May or June, travelers are hedging their bets, with the uptick concentrated on July and August.

“We have consistently seen that there is pent up demand for travel,” EasyJet Chief Executive Officer Johan Lundgren said in the statement. “This surge in bookings shows that this signal from the government that it plans to reopen travel has been what U.K. consumers have been waiting for.”

Shares of EasyJet rose as much as 12% in London, a day after gaining 7.3% in response to Johnson’s plan to gradually reopen the economy. TUI surged as much as 8.3% Tuesday, while Ryanair Holdings Plc and British Airways owner IAG SA also added to Monday’s advance.

Bookings for flights from the U.K. jumped 337% in a few hours, EasyJet said late Monday. Sales of package holidays soared 630%, the low-cost carrier said.

Sunny spots such as Malaga, Alicante and Palma in Spain, Faro in Portugal and the Greek island of Crete are among top destinations, EasyJet said. While travel may reopen sooner, August is the most popular time frame.

While the sales validate optimism for customer demand, the outlook for travel early in summer is cloudy.

What Bloomberg Intelligence says:

“We believe demand will recover quickest at Ryanair, Wizz Air and other low-cost carriers. A slower pace is likely at full-service airlines such as IAG, as the rebound in long-haul travel may not be as quick”

—Rob Barnett, BI analyst

TUI said it won’t operate any holidays until May 17. The company will seek to encourage customers to travel earlier in the season by extending a policy that allows them to rebook trips planned through the end of June for free.

“We will continue to work closely with the government so people can look forward to a well-deserved break away, after what has been a very difficult year for many,” said Andrew Flintham, Managing Director TUI UK and Ireland.