A surge in speculative interest in the U.S. LNG export boom has pushed open interest in natural gas futures to an all-time high, traders said on Nov. 30.

Open interest, which measures the number of contracts outstanding, in the Henry Hub front-month hit 386,826 on the New York Mercantile Exchange on Nov. 29, topping the previous high of 366,383 set in May 2016, according to Reuters data going back to 1990.

“There has been a narrative around the market that the LNG exports are going to be the difference maker this winter, in terms of getting supplies tight and prices higher,” said John Kilduff, partner at energy hedge fund Again Capital LLC in New York.

“The thesis is attracting a lot of interest,” he said, noting “the 11-15 day weather models recently exploded, forecasting a fierce cold air mass by mid-month December. The fuse appears lit.”

Futures for calendar 2018 have been trading at a premium over calendar 2019 since August 2016 due primarily to expectations of rising exports next year.

The U.S. is expected to be a net gas exporter on an annual basis in 2017 for the first time in 60 years, due in part to sharp growth in LNG shipments abroad.

The country, which was not exporting any LNG at the start of 2016, is expected to have the world’s third-biggest export capacity of the fuel by the end of 2018, behind only current market leaders Australia and Kuwait.

That rapid growth in LNG exports was due to the ramp up of four 0.6-billion cubic feet per day (Bcf/d) liquefaction trains at Cheniere Energy Inc.’s (NYSE MKTS: LNG) Sabine Pass LNG export facility in Louisiana over the past two years. The first of those trains entered service in February 2016.

By the end of the year, another LNG export facility is expected to join Sabine Pass when Dominion Energy Inc.’s (NYSE: D) 0.7-bcfd Cove Point terminal in Maryland enters service.

In 2018, three more U.S. liquefaction trains are expected to enter service—a 0.3-bcfd unit at Kinder Morgan Inc.’s (NYSE: KMI) Elba Island facility in Georgia, a 0.7-bcfd unit at Freeport LNG’s Freeport facility in Texas and a 0.6-bcfd unit at Cheniere’s Corpus Christi facility in Texas.