Drought conditions in Brazil has pushed up coffee exchange traded notes, with coffee futures trading at two-year highs.

The iPath Dow Jones-UBS Coffee Total Return Sub-Index ETN (NYSEArca: JO) and iPath Pure Beta Coffee ETN (NYSEArca: CAFÉ) both gained 3.4% Thursday. Coffee has been the best performing asset so far this year, with JO up 83.1% and CAFE up 76.0% year-to-date. [Brazil’s Bad Weather Revives Coffee ETN Rally]

ICE coffee futures were up 3.1% Thursday, trading around $2.061 per pound.

Coffee output from Brazil is expected to dip 4.5% year-over-year to 47 million 60-kilogram bags of beans this season, Reuters reports. The Coffee Crops Council warned that output this year could dip as low as 40.1 million bags.

Some believe the drought induced crop damage could leave a lasting effect.

“People are waking up to the fact that this isn’t a one-year issue, it’s at least a two-year issue,” an European analyst said in the article. “The drought is potentially undermining the whole structure of production of the coming years because the trees are so severely weakened.”

Coffee prices have surged this year on the record heat in January and February, along with continued forecasts for dry weather in Brazil, the world’s largest producer of coffee. Minas Gerais, which produces half of Brazil’s coffee, estimates that as much as 45% of the crop may have been damaged due to the dry weather.