Diesel prices unexpectedly dropped 10 cents a litre in New Brunswick on Wednesday night, following a special meeting of the province's Energy and Utilities Board.
It is one of the biggest single-day decreases in the price of any fuel the province has seen, says CBC reporter Robert Jones.
The price reduction is expected to save New Brunswick consumers about $1 million a week, he said.
The EUB ruled that the end of winter-blend pricing on April 1 required an immediate price reduction.
Oil companies add kerosene to diesel during the winter months to prevent freezing, but aren't allowed to charge extra for it after April 1.
Removing kerosene from the price made such a difference, it triggered the province's rarely used interrupter clause, said EUB spokesperson David Young.
The clause forces the EUB to reset prices when price changes in New York exceed eight cents a litre in a single day.
The maximum price for diesel is now $1.40 per litre. It was selling for $1.35.9 per litre in Rothesay on Thursday.