Sea-Tac Airport continues to see huge passenger growth this year, up 6.1 percent through June, according to Port of Seattle numbers.

June is the start of the summer travel season, the airport’s busiest. The traffic at Sea-Tac Airport is up 7.3 percent over June of 2017. After the busy summer season, airport executives expect things will settle down for the fall and winter season, forecasting a total growth rate of five percent for all of 2018.

That traffic increase over 2018 is still a sharp rise from 2017, which saw overall growth at 2.9 percent, the slowest in years. Growth peaked at 12.9 percent in 2015, backing down to 8 percent in 2016.

For the past five years, Sea-Tac Airport was the fastest growing airport in the nation, according to airport spokesman Perry Cooper. Putting this into perspective, the most eye-popping numbers are what’s happened to overall passenger growth during that five-year period, overall passenger traffic up 43 percent.

It’s all set off a building boom at the airport to catch up. An eight gate expansion and upgrade to the North Satellite is well underway. So is construction of the new international arrivals terminal.

Along the departure drives sit another six gates connected by specialized busses to remote hardstands away from the terminal. A hardstand allows planes to park and connect up to portable ramps loading and unloading passengers. There are 15 hard stands, along with what will be 10 waiting areas once the additional six are opened in late September or early October.

The Port of Seattle has been working on the hardstand plan for a while, but it’s really taken off this summer. Cooper said there were about five flights a day using the hardstands in May. Now, it’s 25 to 30 flights a day. The hardstands are operated by a consortium of airlines using equipment leased from the Port of Seattle.