Premier Doug Ford is raising concerns about price-gouging at Ontario gas stations, calling a surge in prices overnight "disgusting."

Gas prices jumped an average of 14 cents per litre overnight in the GTA, climbing to levels not seen in nearly two years as the switch from winter fuel to a more expensive summer blend pushes up the price at the pumps.

Gas prices for most of Ontario now sit at around 179.9 cents a litre.

“It is disgusting what the oil companies are doing. They are saying we have to upgrade the gas in the summer,” Ford said while answering questions at an unrelated news conference in Oakville on Thursday morning.

“Do you let your tanks at the gas stations drain and do you have these tankers come up… to put the fresh gas in or you using the old gas and charging the higher cost?”

He said after reaching out to friends in the U.S., he discovered that the price of gas has not similarly increased in Chicago and Minnesota.

“Either you are putting the fresh stuff in last month or you are gouging the people right now,” Ford reiterated.

Patrick De Haan, head of petroleum analysis at fuel savings website GasBuddy in Chicago, told CTV News on Wednesday that the increase is happening now in the eastern parts of Canada.

"Some gas stations have already raised their price, in essence, but some others may not for the next day or two," De Haan said. "So over the next several days, the averages will continue to rise as more stations raise their price.”

Dan McTeague, the president of Canadians for Affordable Energy, told CP24 on Thursday that in past years, that switchover from winter to summer fuel typically results in an increase of about six to 10 cents per litre.

“In warmer (weather)… refiners are required by law to change the blend of gasoline to introduce things that become less volatile. The most important ingredient is alkylates and alkylates are extremely expensive,” he said. “The cost of that product has really skyrocketed.”

McTeague said the good news is there will be a five cents per litre drop at the pumps by Friday.

While 179.9 cents per litre may be the highest price motorists have seen in quite some time, it is well short of the record high, which McTeague said was set on June 11, 2022 when the price of gas hit 215 cents per litre.

Gas prices typically remain elevated during the summer months but come back down again in mid-September when the cheaper winter fuel blend returns, McTeague said.