After pulling through its worst drought in decades, Brazil, the world’s largest supplier of coffee, is expected to experience an extended period of poor harvests, boosting coffee futures and related exchange traded notes.

The iPath Dow Jones-UBS Coffee Total Return Sub-Index ETN (NYSEArca: JO) increased 5.7% Tuesday while iPath Pure Beta Coffee ETN (NYSEArca: CAFÉ) rose 5.2%. Coffee has been the best performing commodity this year, with JO up 62.8% and CAFE up 59.0% year-to-date. [Another Caffeinated Rally for Coffee ETNs]

ICE coffee futures were up 4.7% Tuesday, trading around $1.965 per pound. [Jumpin’ Java: More Upside Seen for Coffee ETNs]

Brazil is heading for its first three-year decline in output since 1965, Bloomberg reports.

The National Coffee Council calculates that Brazilian production could plummet as much as 18% to 40.1 million bags when harvests end next month. Additionally, farmers could produce less than 40 million bags in 2015. Citigroup (NYSE: C) is less optimistic, predicting a global production deficit to last into 2016.

Meanwhile, rising demand has also been supporting the elevated prices. The International Coffee Organization expects a global production deficit of as much as 10 million bags in the year starting Oct. 1 while Volcafe Ltd. projects a deficit at 11.3 million bags.

“The market is vulnerable to the upside given all the problems in Brazil,” Donald Selkin, chief market strategist at National Securities Corp., said in the article. “People are anticipating tighter supplies and are waiting for more dramatic weather developments.”