Oil futures on Thursday finished with a 25% gain for the month of April to tally their largest monthly gain in almost six years, as a weekly decline in crude inventories at the U.S. storage hub for the first time in months fed expectations that the nation’s production and supply glut will soon start to ease.

Meanwhile, natural-gas futures rallied to the highest settlement level in about a month as weekly U.S. supplies rose less than expected.

June crude tacked on $1.05, or 1.8%, to settle at $59.63 a barrel on the New York Mercantile Exchange. Tracking the most-active contracts, prices were up about 25% for the month—the biggest monthly gain since May 2009, FactSet data show. Meanwhile, Brent crude for June delivery on London’s ICE Futures exchange—the global benchmark—finished up 94 cents, or 1.4%, to end at $66.78 a barrel—up about 21% from the settlement of most-active contract on March 31.

U.S. weekly crude-oil inventories rose for a 16th straight week, according to data from the Energy Information Administration Wednesday. But supplies at the Cushing, Okla. storage hub fell for the first time since November, according to analysts.

This month bloomed into the “largest monthly rally for crude oil since May 2009, as prices find affirmation in [Wednesday’s] weekly U.S. inventory report from the first draw at Cushing, Okla. (where West Texas Intermediate is priced) in 21 weeks,” said Matt Smith, a commodity analyst at Schneider Electric, in a note. The U.S. shale boom and surge in domestic oil production had sent storage levels at Cushing to record highs. Traders have been expecting oil-production levels to show sizable declines following several weeks of decreases in the number of U.S. rigs actively drilling for oil.

Dollar-denominated oil prices also got a boost Thursday from a weaker dollar. For oil, “the path of least resistance remains higher from here as the bulls have some momentum and the short side of the market remains ‘overcrowded’, leaving futures vulnerable to swift short-squeeze rallies,” said Tyler Richey, an analyst for the 7:00’s Report.

But on Nymex Thursday, natural gas saw the biggest price gains.

The U.S. Energy Information Administration reported Thursday that supplies of natural gas rose by 81 billion cubic feet for the week ended April 24. Analysts surveyed by Platts forecast a climb of between 84 billion cubic feet and 88 billion cubic feet.

June natural gas climbed 14.5 cents, or 5.6%, to $2.751 per million British thermal units. Prices, which settle at their highest level since March 24, were up 4.2% from the settlement of the most-active contract on March 31.

Also on Nymex, petroleum-product prices finished higher as the May contracts expired at the close. May gasoline rose 3.2 cents, or 1.6%, to $2.0497 a gallon, while May heating oil ended at $1.976, up 2.8 cents, or 1.5%. Both were up around 15% for the month.