Temperatures in Brazil's coffee-growing regions recorded -1.2 Celsius (29 Fahrenheit) on Tuesday in southern Minas Gerais, which was the coldest since 1994. 

"I've never seen something like that. We knew it would be cold, we were monitoring, but temperatures suddenly went several degrees down when it was already early morning," said Mario Alvarenga, a coffee producer with two farms in Minas Gerais, Brazil's largest producing state.

Futures for arabica beans in New York soared more than 7.5% Thursday. Since Tuesday's frost, future prices are up more than 23.5%, hitting 6.5-year highs.