There will be a "significant" change to the price of gasoline in Nova Scotia at midnight — two days before the normal adjustment day — after the Utility and Review Board invoked the interrupter clause.

The board has given no indication on whether the price will go up or down, but the price of oil has been sliding since the beginning of the summer after bouncing above $60 in June. Current prices are hovering at around $40 US a barrel.

The interrupter clause is used by the Utility and Review Board to "respond to sudden and significant spikes, up or down, in petroleum product prices."

"This change is necessary due to significant shifts in the market price of gasoline," it said in a statement.

Bob Jones, the CBC's gas guru, predicts prices will fall.

The board said the price of diesel will not be affected in Tuesday night's adjustment.

The Utility and Review Board considers using the interrupter clause for petroleum products when the market price for that product fluctuates by six to eight cents per litre versus the weekly price set by the board.

The last time the interrupter clause was used was in March when the price of diesel was slashed 6.4 cents a litre. It was last used to adjust the price of gas in February.